powerpoint to accompany hole’s human anatomy and ... 4.4: energy for metabolic reactions •...

1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Chapter 04

*Lecture Outline

*See separate Image PowerPoint slides for all

figures and tables pre-inserted into

PowerPoint without notes.

2

4.2: Metabolic Processes

Cellular metabolism There are two (2) types of metabolic

pathways:

•Anabolism

• Larger molecules

are made from

smaller ones

• Requires

energy

•Catabolism

• Larger molecules

are broken down into

smaller ones

• Releases

energy

3

Anabolism

• Anabolism provides the materials needed for cellular

growth and repair –joins simple molecules to form

larger molecules of glycogen

•Example: Dehydration synthesis

• Type of anabolic process

• Used to make polysaccharides, triglycerides, and proteins

• Produces water CH2OH

H H

OH

O

H OH

Monosaccharide +

H HO

H

OH

H H

OH

O

H OH

Monosaccharide

H HO

H

OH

H H

OH

O

H OH

Disaccharide

H2O

Water +

H HO

H H H

OH

O

H OH

H O

H

OH

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

CH2OH CH2OH CH2OH

Glycerol and fatty acid molecules join by

dehydration synthesis in fat cells to form

fat molecules. Three hydrogen atoms are

removed from a glycerol molecule and

an –OH group is removed from each of

the three fatty acid molecules. All this

results in 3 water molecules and a single

fat molecule.

(next slide) 4

Amino acid

N

H

H

C C

H

R

Dipeptide molecule + +

Peptide

bond

Amino acid

N

H

H

C C

H H

H

R H

O

N

H

H

C C

H

R H

O

N

H

C C OH

R

H

O O

N

H

H

C C

H

R

N

H

C C OH

R

H

O O

Water


O O

H2O

5

Anabolism

H C

H

Glycerol 3 fatty acid molecules +

OH HO

H C OH HO

H C

C

C

C OH HO

H

O

O

C

C

C

O

O

O

H C

H

Fat molecule (triglyceride) +

H C

H C O

O

O

H

3 water

molecules

(CH2)14 CH3

(CH2)14 CH3

(CH2)14 CH3

(CH2)14 CH3

(CH2)14 CH3

(CH2)14 CH3

H2O

H2O

H2O


O

Catabolism

Hydrolysis can decompose carbohydrates,

lipids and proteins using a water molecule

So, with dehydration synthesis molecules are

joined together and the by product is water.

BUT

Hydrolysis uses water to decompose bonds

6

7

Catabolism

• Catabolism breaks down larger molecules into smaller ones

• Example: Hydrolysis • A catabolic process

• Used to decompose carbohydrates, lipids, and proteins

• Water is used to split the substances

• Reverse of dehydration synthesis

CH2OH

H H

OH

O

H OH

Monosaccharide +

H HO

H

OH

H H

OH

O

H OH

Monosaccharide

H HO

H

OH

H H

OH

O

H OH

Disaccharide

H2O

Water +

H HO

H H H

OH

O

H OH

H O

H

OH


CH2OH CH2OH CH2OH

The next slide shows amino acids

breaking down into dipeptides by

using H20 to decompose the bonds

8

Catabolism

Amino acid

N

H

H

C C

H

R

Dipeptide molecule + +

Peptide

bond

Amino acid

N

H

H

C C

H H

H

R H

O

N

H

H

C C

H

R H

O

N

H

C C OH

R

H

O O

N

H

H

C C

H

R

N

H

C C OH

R

H

O O

Water


O O

H2O

H C

H

Glycerol 3 fatty acid molecules +

OH HO

H C OH HO

H C

C

C

C OH HO

H

O

O

C

C

C

O

O

O

H C

H

Fat molecule (triglyceride) +

H C

H C O

O

O

H

3 water

molecules

(CH2)14 CH3

(CH2)14 CH3

(CH2)14 CH3

(CH2)14 CH3

(CH2)14 CH3

(CH2)14 CH3

H2O

H2O

H2O


O

9

4.3: Control of Metabolic

Reactions

• Metabolic reactions include hundreds of

chemical changes that must occur in

particular sequences.

All cells conduct specialized metabolic processes.

There are hundreds of very specific chemical

changes that must occur in particular sequences.

10

Enzymes are a catalyst that is not absorbed and can

be used over and over. EACH enzyme is specific

acting only on (its’ own) molecule called its

SUBSTRATE. Each enzyme must be able to

recognize its specific substrate.

Also explained in next slide

11

12

• Enzymes

• Control rates of metabolic reactions

• Lower activation energy needed to start reactions

• Most are globular proteins with specific shapes

• Not consumed in chemical reactions

• Substrate specific

• Shape of active site determines substrate

Product molecule

Active site

(a) (b) (c)

Substrate molecules

Unaltered

enzyme

molecule

Enzyme-substrate

complex

Enzyme

molecule


Enzyme Action

Enzymes temporarily attach to the active sites

on the substrate as the numbers increase the

reaction speeds up. Sequences of enzymes

are controlled reactions called metabolic

pathways. Many enzyme names are derived

from the names of their substrates with the

suffix—ase.

Examples are:

The lipid splitting enzyme is lipase

The lactose splitting enzyme is lactase

13

14

Enzyme Action

• Metabolic pathways • Series of enzyme-controlled reactions leading to formation of a

product

• Each new substrate is the product of the previous reaction

• Enzyme names commonly:

• Reflect the substrate

• Have the suffix – ase

• Examples: sucrase, lactase, protease, lipase

Substrate

1

Enzyme A Substrate

2

Enzyme B Substrate

3

Enzyme C Substrate

4

Enzyme D Product


15

Regulation of Metabolic Pathways

Limited number of regulatory enzymes

—becomes ineffective at high concentrations

Negative feedback

Inhibition

Substrate

1

Substrate

2

Enzyme B Substrate

3

Enzyme C Substrate

4

Enzyme D Product

Rate-limiting

Enzyme A


16

Cofactors and Coenzymes

• Cofactors

• Make some enzymes active

•Non protein component

•Ions or coenzymes

•Many enzymes are inactive until they

combine with a particular cofactor •

•Coenzymes

• Organic molecules that act as cofactors

• Vitamins (see next slide)

This is why we need some vitamins and

minerals. Many enzymes are inactive until

they combine with a particular cofactor.

Examples are things we are aware of such as:

Vitamin A for skin

Vitamin C for collagen and absorbing iron

Vitamin D for bones and teeth

17

18

Factors That Alter Enzymes

• Factors that alter enzymes:

• Heat

• Radiation

• Electricity

• Chemicals

• Changes in pH

Chemicals with extreme pH values can

denature or alter the shape of the enzymes.

Example: Cyanide denatures respiratory enzymes

19

4.4: Energy for Metabolic

Reactions

• Energy is the capacity to change something; it is the

ability to do work

• Common forms of energy:

• Heat Cellular respiration is the process that

• Light transfers energy from molecules such

• Sound as glucose and makes it available for

• Electrical energy cellular use

• Mechanical energy

• Chemical energy

• Energy can be changed from one form to another.

Through cellular respiration, energy is transferred

from molecules to make it available for cellular use.

ATP is the primary energy carrying molecule in the cell.

ATP = an adenine, a ribose, and 3 phosphates in a chain.

The second and third phosphates are attached by a high-

energy bond, and the chemical energy stored may be quickly

transferred to another molecule.

Cells burn glucose in a process called oxidation. The

energy released by oxidation of glucose is harnessed to

promote cellular metabolism. In cells enzymes initiate

oxidation by lowering the activation energy. By transferring

energy to ATP cells are able to capture almost half of the

energy released in the form of chemical energy.

20

Adenosine triphosphate

21

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22

ATP Molecules

•Adenosine triphosphate (ATP) carries energy in a form that the

cell can use

• Each ATP molecule has three parts:

• An adenine molecule

• A ribose molecule

• Three phosphate molecules in a chain

Energy transferred

and utilized by

metabolic reactions

when phosphate bond

is broken

Energy transferred from

cellular respiration used

to reattach phosphate

P

P P

P

P P P


23

Release of Chemical Energy

• Chemical bonds are broken to release energy

• We burn glucose in a process called oxidation

Cellular reaction includes aerobic (o2) and anaerobic

(no o2) reactions. For each glucose molecule

decomposed by cellular respiration up to 38 molecules

of ATP can be produced.

24

Cellular Respiration

occurs in a series of reactions:

1. Glycolysis

2. Citric acid cycle (Kreb’s Cycle)

3. Electron transport chain (ETC)

Produces

• Carbon dioxide

• water

• ATP (chemical energy)

• heat

Includes:

• Anaerobic reactions (without O2) - produce little ATP

• Aerobic reactions (requires O2) - produce most ATP

The next three slides are about Glycolysis.

It means “the breaking of glucose”.

It does not require o2.

6- carbon sugar glucose is broken down in the

cytosol into two 3-carbon pyruvic acid

molecules with a net gain of 2 ATP and the

release of high-energy electrons.

25

26

Glycolysis

• Series of ten reactions

• Breaks down glucose into 2 pyruvic acid molecules

• Occurs in cytosol

• Anaerobic phase of cellular respiration

• Yields two ATP molecules per glucose molecule

Summarized by three main phases or events:

1. Phosphorylation

2. Splitting

3. Production of NADH and FAD

(Nicotinamide Adenine Dinucleotide plus Hydrogen)

(flavin adenine dinucleotide)

27

Glycolysis

Event 1 - Phosphorylation

• Two phosphates

added to glucose

• Requires ATP

Event 2 – Splitting (cleavage)

• 6-carbon glucose split

into two 3-carbon

molecules

(The electron carrier

NADH is produced)

Phase 1

priming

Phase 2

cleavage

Phase 3

oxidation and

formation of

ATP and release

of high energy

electrons

2 ADP

2 NADH + H+

2 NAD+

2 NADH + H+

2 NAD+

P

ATP

P P

P

Glyceraldehyde

phosphate

Glucose

Dihydroxyacetone

phosphate

2

4 ADP

ATP 4

Fructose-1,6-diphosphate

O2

2 Pyruvic acid

2 Lactic acid To citric acid cycle

and electron transport

chain (aerobic pathway)

Carbon atom

Phosphate P

P


O2

28

Glycolysis

Event 3 – Production of NADH and ATP

• Hydrogen atoms are released

• Hydrogen atoms bind to NAD+

to produce NADH

• NADH delivers hydrogen and

high energy electrons to electron

transport chain if oxygen is

available

• ADP is phosphorylated to

become ATP

• Two molecules of pyruvic acid

are produced

• Two molecules of ATP are

generated

Phase 1

priming

Phase 2

cleavage

Phase 3

oxidation and

formation of

ATP and release

of high energy

electrons

2 ADP

2 NADH + H+

2 NAD+

2 NADH + H+

2 NAD+

P

ATP

P P

P

Glyceraldehyde

phosphate

Glucose

Dihydroxyacetone

phosphate

2

4 ADP

ATP 4


O2

2 Pyruvic acid




Carbon atom

Phosphate P

P


O2

29

Anaerobic Reactions

• If oxygen is not available:

• Electron transport

system cannot accept

new electrons from

NADH

• Pyruvic acid is

converted to lactic acid

• Glycolysis is inhibited

• ATP production is less

than in aerobic reactions

Phase 1

priming

Phase 2

cleavage

Phase 3

oxidation and

formation of

ATP and release

of high energy

electrons

2 ADP

2 NADH + H+

2 NAD+

2 NADH + H+

2 NAD+

P

ATP

P P

P

Glyceraldehyde

phosphate

Glucose

Dihydroxyacetone

phosphate

2

4 ADP

ATP 4


O2

2 Pyruvic acid




Carbon atom

Phosphate P

P


O2

Glycolysis continues as NADH + H delivers

electrons to the electron transport chain. This can

only happen in the presence of o2 under anaerobic

conditions the electron can’t be unloaded or accept

new electrons. NADH +H delivers electrons and

hydrogens back to the pyruvic acid in a reaction that

forms lactic acid.

If enough o2 is available this reaction will yield

carbon dioxide and water and yield up to 36 ATP

molecules per glucose

30

31

Aerobic Reactions

• If oxygen is available:

• Pyruvic acid is used

to produce acetyl CoA

• Citric acid cycle

begins

• Electron transport

chain functions

• Carbon dioxide and

water are formed

• Up to 36 molecules

of ATP are produced

per each glucose

molecule

ATP 2

ATP 2

Glucose

Pyruvic acid Pyruvic acid

Acetyl CoA

CO2

2 CO 2

Citric acid

O 2

H 2 O

2e – + 2H +

Electron transport chain

ATP 32-34

Cytosol

Mitochondrion

High energy

electrons (e–) and

hydrogen ions (H+)

High energy


hydrogen ions (h+)

Oxaloacetic

acid

High energy


hydrogen ions (H+)


Citric Acid Cycle

1. one ATP is produced directly for each

citric acid molecule

2. for each citric acid molecule 8 Hydrogen

atoms with high energy electrons are

transferred to Hydrogen carriers.

5. as 6 carbon citric acid reacts to form the 4

carbon oxaloacetic acid two CO2 molecules

are produced

page 130

32

33

Citric Acid Cycle

• Begins when acetyl CoA

combines with oxaloacetic

acid to produce citric acid

• Citric acid is changed into

oxaloacetic acid through a

series of reactions

• Cycle repeats as long as

pyruvic acid and oxygen are

available

• For each citric acid molecule:

• One ATP is produced

• Eight hydrogen atoms are

transferred to NAD+ and

FAD

• Two CO2 produced

Citric acid cycle

ADP + ATP

Pyruvic acid from glycolysis

Citric acid

(start molecule)

Acetyl CoA

(replenish molecule)

Acetic acid

Oxaloacetic acid

(finish molecule)

Isocitric acid

CO 2

CO 2

CO 2

Succinyl-CoA Succinic acid FAD

FADH 2

Fumaric acid

Malic acid

Cytosol

Mitochondrion

NADH + H +

NAD +

NADH + H +

NAD +

NADH + H +

NAD +

CoA

CoA

CoA

CoA

P

NADH + H +

NAD +

P

CoA

Carbon atom

Phosphate

Coenzyme A

-Ketoglutaric acid


The Hydrogen and electron carriers that

have been generated by glycolysis and

citric acid cycle now hold most of the

energy contained in the original glucose

molecules.

34

35

Electron Transport Chain

ATP ADP + ATP synthase

Electron transport chain

Energy

P

2H+ + 2e–

2e–

2H+

NADH + H+

NAD+

2H+ + 2e–

FADH2

FAD

O 2

H2O

Energy

Energy


• NADH and FADH2 carry hydrogen and high energy electrons to the

ETC

• ETC is a series of enzyme complexes located in the inner membrane of

the mitochondrion

• Energy from electrons transferred to ATP synthase

• ATP synthase catalyzes the phosphorylation of ADP to ATP

• Water is formed (Oxygen is the final electron “carrier”)

36

Summary of Cellular

Respiration

Glycolysis

Cyto

so

l M

ito

ch

on

dri

on

A T P 2

Glucose

High-energy electrons (e–)



2e – and 2H +

A T P 2

H 2 O O 2

A T P 32–34

CO 2

Pyruvic acid Pyruvic acid

2 CO 2

Acetyl Co A

Citric acid Oxaloacetic acid

1

3

4

2

Glycolysis

The 6-carbon sugar glucose is broken down in the

cytosol into two 3-carbon pyruvic acid molecules

with

a net gain of 2 ATP and release of high-energy

electrons.

Citric Acid Cycle

The 3-carbon pyruvic acids generated by glycolysis

enter the mitochondria. Each loses a carbon

(generating CO2 and is combined with a coenzyme to

form a 2-carbon acetyl coenzyme A (acetyl CoA). More

high-energy electrons are released.

Each acetyl CoA combines with a 4-carbon oxaloacetic

acid to form the 6-carbon citric acid, for which the cycle

is named. For each citric acid, a series of reactions

removes 2 carbons (generating 2 CO2’s), synthesizes

1 ATP, and releases more high-energy electrons.

The figure shows 2 ATP, resulting directly from 2

turns of the cycle per glucose molecule that enters

glycolysis.

Electron Transport Chain

The high-energy electrons still contain most of the chemical energy of the original

glucose molecule.

Special carrier molecules bring the high-energy electrons to a series of enzymes that

convert much of the remaining energy to more ATP molecules. The

other products are heat and water. The function of oxygen as the final electron acceptor

in this last step is why the overall process is called aerobic respiration.

Electron

transport

chain

Citric acid

cycle


37

Carbohydrate Storage

• Carbohydrate molecules from foods can enter:

• Catabolic pathways for energy production

• Anabolic pathways for storage

Remember some amino acids are scavenged?

Carbohydrate molecules can enter catabolic pathways

and be used to supply energy OR they can enter

anabolic pathways and be stored as glycogen ( for

energy later, this assures that cells throughout the

body have a continual supply of glucose.) OR react to

form some twenty different amino acids.

38

Carbohydrate Storage

• Excess glucose stored as:

• Glycogen (primarily by liver and muscle cells)

• Fat—more carbs ingested than can be used

• Converted to amino acids

Hydrolysis

Monosaccharides

Energy + CO2 + H2O Glycogen or Fat Amino acids

Carbohydrates

from foods

Catabolic

pathways Anabolic

pathways


39

4.6: Nucleic Acids and

Protein Synthesis

• Instruction of cells to synthesize proteins comes from a nucleic

acid, deoxyribonucleic acid (DNA)

•Enzymes control the metabolic pathways essential for cell

survival cells must have information for producing these

specialized protein. The information is held in the sequences of

building blocks of DNA.. The correspondence between a unit of

DNA information and a particular amino acid is the genetic code

Enzymes control the metabolic pathways

essential for cell survival. Cells must have

information for producing these specialized

proteins. The information is held in the

sequence of building blocks of DNA. The

correspondence between a unit of DNA

information and a particular amino acid is the

genetic code.

40

A DNA sequence that contains the information for

a protein is a gene. Enzymes are proteins that

control metabolism at the chemical level. The

complete set of genetic instructions is the genome.

Only a small part of the human genome encodes

protein. The rest controls which proteins are

produced in a particular cell, under particular

circumstances called gene expression.

41

42

Genetic Information

• Gene – segment of DNA that codes for one protein

• Genetic information – instructs cells how to construct

proteins; stored in DNA

• Genome – complete set of genes

• Genetic Code – method used to translate a sequence of

nucleotides of DNA into a sequence of amino acids

Structure of DNA

43

• made of 2 strands of

nucleotides which spiral

(double helix)

• Each nucleotide

contains: 5-C sugar

(deoxyribose),

phosphate, and a

nitrogenous base

(adenine, guanine,

cytosine, or thymine)

• The backbone of each

strand is a sugar-

phosphate chain

• The bases of

complementary strands

hydrogen bond to each

other: C-G, A-T

• DNA wrapped about

histones forms

chromosomes

44

Structure of DNA Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

S

P

S

P

S

P

S

P

S

P

S

P

B

B

B

B

B

B

S

P

S

P

S

P

B

B

B

S

P

S

P

S

P

S

P

S

P

S

P

B

B

B

B

B

B

S

S

S

S

S

S

P

P

P

P

P

P

B

B

B

B

B

B


45

Structure of DNA

G C

G C

A

P

G C P

T P

P

C G

P

G

P

C

P

A

P

P

P

Thymine (T)

Cytosine (C) Guanine (G)

Adenine (A)

Polynucleotide

strands

Segment

of DNA

molecule

Chromatin Globular

histone

proteins

Interphase

chromosome

Metaphase

chromosome

(c)

(b)

(a) Hydrogen

bond

G

A

T

C

T

G C

A T

G C

A

A

T

A


46

4.1 From Science to Technology

DNA Profiling Frees A Prisoner

Page 137

47

DNA can be a double-edged sword.

Where it rightfully exculpates some, like Timothy Cole,

it wrongfully inculpates others. Lydia Fairchild's DNA

results did not match that of her own children when she

applied for welfare. "Fairchild was not only denied

government assistance,...she was now suspected of

possibly acting as a paid surrogate mother and committing

welfare fraud." She'd have lost custody of her kids, had her

lawyer not researched the medical phenomena known as chimerism.

Sometimes two fertilized eggs meant to be twins fuse

into "one fetus that carries two distinct

genetic codes -- two separate strands of DNA."

So while DNA from Lydia's hair and skin cells didn't match that of her

kids, those from other body tissues, like her cervical cells, did match.

Her story is an example of overestimating the validity of DNA rulings.

http://4.bp.blogspot.com/-6aeme-0lWug/TVXWDfdz88I/AAAAAAAAAS4/nK_4CfLlEgI/s1600/abc_chimera_lydia_060815_nr.jpg

http://abcnews.go.com/Primetime/story?id=2315693&page=4

48

Sometimes DNA evidence only leads police on a wild

goose chase. In Germany, there was a woman serial

killer, whose trail was as prolific as it was

unpredictable. Her DNA showed up repeatedly at

crime scenes, but she managed to evade police capture.

She seemed almost ghostly to the puzzled authorities

and frightened public - Having no other clues to her

existence besides her reliably present DNA calling

card. Turns out a little old lady who worked in the

factory that made the DNA swabs was unknowingly

contaminating them. Oops.

http://www.nytimes.com/2013/09/17/science/dna-

double-take.html?pagewanted=all&_r=0

http://www.time.com/time/world/article/0,8599,1888126,00.html

http://www.time.com/time/world/article/0,8599,1888126,00.html

49

DNA Replication

• Hydrogen bonds break between bases

• Double strands unwind and pull apart

• New nucleotides pair with exposed bases

• Controlled by DNA polymerase

When a cell divides, each newly formed

cell receives a copy of the entire

genome(complete set of genes). All cells

except the sperm and egg receive two

copies of the genome in two sets of

chromosomes.

As DNA replication begins, Hydrogen bonds

break between the strands and they unwind

and separate DNA polymerase catalyzes the

new pairing which results in two complete

DNA molecules each with one new and one

original strand. Genetic information

specifies how these ladders line up as well

as information for determining which

genes are accessed for their information.

50

51

DNA Replication

C

C

A T

C

C G

G

C

C

C G

A

A

T

T

C G

C

A T

G

G

G

G

G

G

G G

G

C C

C G

S

Newly forming

DNA molecules

G1

Cytokinesis

Restriction

checkpoint

Apoptosis

Original DNA

molecule

S phase:

genetic

material

replicates

G2 phase

G1 phase:

Cell growth Proceed

to division

Remain

specialized

G2

T A A

T A

T A

A T

T A A

A

A

A

A


52

Genetic Code

• Specification of the correct sequence of amino acids in a

polypeptide chain

• Each amino acid is represented by a triplet code of DNA

bases

• The base sequence of a gene then determines the amino

acid sequence in a polypeptide

• Since DNA stays in the nucleus, and proteins are made

in the cytoplasm, DNA’s code must be copied and carried

to the cytoplasm. RNA molecules accomplish this transfer

of the genetic code.

RNA Molecules

• Single strand of nucleotides

• Each nucleotide contains: ribose, phosphate,

base (A, G, C, and Uracil instead of Thymine)

• Shorter than DNA

• Different types: mRNA (carries code from

DNA to ribosome), tRNA (brings amino acids

to ribosome), rRNA (a component of

ribosomes)

53

Protein Synthesis involves 2 steps, each requiring

RNA and enzymes

• Transcription occurs in the nucleus and

is the process of copying DNA information into

an RNA sequence

• Translation occurs at the ribosomes in

the cytoplasm as the code is transferred to a

growing chain of amino acids

54

RNA Molecules

55

RNA Molecules

• Transcription of Messenger

RNA (mRNA): • A section of DNA opens up (just

where the gene coding for the

particular protein is)

• mRNA nucleotides pair up with the

DNA bases on one side---uracil is used

instead of thymine

• mRNA moves away and DNA closes

up

• Controlled by RNA polymerase

The mRNA now goes through nuclear

pore and attaches to a ribosome in the

cytoplasm.


DNA RNA

S

G

S

C

S

S

S

S

C

G

T

A

S

S

S

S

G

C

A

U

Dir

ectio

n o

f “r

ea

din

g”

co

de

P

P

P

P

P

P

P

P

P

P

• Each tRNA molecule has an attachment point for a

specific amino acid

• Each tRNA also has a region of 3 bases called an

anticodon which is attracted to complementary mRNA

codons

• As the ribosome moves down the mRNA strand,

tRNA’s bringing their amino acids are attracted to the

mRNA codons

Page 142

56

Protein Synthesis

Protein Synthesis

57

58

Protein Synthesis

Messenger

RNA

1 DNA

information

is copied, or

transcribed,

into mRNA

following

complementary

base pairing

2 mRNA leaves

the nucleus

and attaches

to a ribosome

3 Translation begins as tRNA anticodons

recognize complementary mRNA codons,

thus bringing the correct amino acids into

position on the growing polypeptide chain

4 As the ribosome

moves along the

mRNA, more amino

acids are added

5 At the end of the mRNA,

the ribosome releases

the new protein

6

Amino acids

attached to tRNA

Polypeptide

chain

Cytoplasm DNA

double

helix

DNA

strands

pulled

apart

Transcription

(in nucleus)

Translation

(in cytoplasm)

Nucleus

C

Codon 1

Codon 2

Codon 3

Codon 4

Codon 5

Codon 6

Codon 7

G G

G G

G

A

A

A

U

U

C

C C

C

C

C

G G

G

A Methionine

Glycine

Amino acids

represented

Serine

Alanine

Threonine

Alanine

Glycine

DNA

strand

Messenger

RNA

A T

A

A

T

T

T

A T A T

A T

A T

A T

U A

U A

U A

G C

C

G C G C

G C

G C G C

G C

G

G

C

C

G C

C G U A C G C

G

G

G G

G

G

G G

G

G

C

C C

C

C

C

C

C C

C

A

A

A

A

A

T

T A

A T

A T

A T

A T

C G

G C

G C

G C

T A

T A

T A

C G

A T G C

T A C G

T A C G

C G

G C

A T

T A C G

G C

T

T

G

C G

C G

C G

C G

C G C G

C G

C G

Nuclear

pore

tRNA molecules

can pick up another

molecule of the

same amino acid

and be reused


G C

C G

A

G

G

C

U

C

T

C

C

G

A

G

59

Protein Synthesis

Next amino acid

Anticodon

Codons

Growing

polypeptide

chain

1

1

2

2

3

3

4

4

5

5

6

6

7

Ribosome

1

1

2

2

3

3

7

4

4

5

5

6 7

C G U

C U G C G U

Next amino acid

Anticodon

Codons

1

1

2

2

3

3

4

4

5

5

6

6

7

Peptide bond

C U G C G U

C C G C G U

6

Messenger

RNA

Transfer

RNA

Next

amino acid

1

1

2

2

3

3

4

4

5

5

6 7

6 7

U C G G A A A A A A G G G G G G G G C C C C C C C U U




The transfer RNA molecule

for the last amino acid added

holds the growing polypeptide

chain and is attached to its

complementary codon on mRNA.

A second tRNA binds complementarily to the

next codon, and in doing so brings the next

amino acid into position on the ribosome.

A peptide bond forms, linking new amino

acid to the growing polypeptide chain.

The tRNA molecule that brought the last

amino acid to the ribosome is released

to the cytoplasm, and will be used again.

The ribosome moves to a new position at

the next codon on mRNA.

A

A new tRNA complementary to

the next codon on mRNA brings

the next amino acid to be added

to the growing polypeptide chain.

2

1

3

4

Messenger

RNA

Transfer

RNA

Next

amino acid

Transfer

RNA

Messenger

RNA

Transfer

RNA

Growing

polypeptide

chain


60


MicroRNAs Control Gene Expression

Instructions for using the blueprint—they control

specific sets of genes

Page 143

61

4.7: Changes in

Genetic Information

• Only about 1/10th of one percent of the human genome

differs from person to person

•So we are 99.9% the same. The other 1/10 % carry DNA

that affects health and appearance.

62

Nature of Mutations

• Mutations – change in genetic

information

• Result when:

• Extra bases are added or

deleted

• Bases are changed

• May or may not change the

protein

Code for

glutamic

acid

Mutation

Dir

ec

tio

n o

f “re

ad

ing

” c

od

e

Code for

valine

(a) (b)

S

S

S

C

T

A

P

P

P

S

S

S

C

T

T

P

P

P


If a change at the 4th base of a DNA

sequence results in a noticeable or

detectable change & occurs in less than 1%

of the population , it is considered a

mutation. If there is no discernable change

with the DNA variation it is called an SNP

(single nucleotide polymorphism)

63

64

Protection Against Mutation

• Repair enzymes correct the mutations

Mutations can occur spontaneously during

the DNA replication or might be induced in

response to exposure to chemicals or

radiation called mutagens.

Cells can detect and correct using the DNA

damage response. It restores the original

DNA sequence.

65

Inborn Errors of Metabolism

• Occurs from inheriting a mutation that then alters an

enzyme

• This creates a block in an otherwise normal

biochemical pathway

•Since amino acids can connect in different ways they

can “avoid” the bad connection. If one gene is

damaged-the other may provide enough for some

measure of normalcy. Time is a factor. Mutations in

eggs and sperm will be replicated from the start, but

some mutations occur much later and may have lesser

effects.

66


The Human Metabolome

Page 145

Refers to all of the small molecules that

are part of metabolism in a cell, tissue,

organ or an entire organism.

67

Important Points in Chapter 4: Outcomes to be Assessed

4.1: Introduction

Describe the linked pathways of metabolism.

4.2: Metabolic Processes

Compare and contrast anabolism and catabolism.

4.3: Control of Metabolic Reactions

Describe how enzymes control metabolic reactions.

Explain how metabolic pathways are regulated.

68


4.4: Energy for Metabolic Reactions

Explain how ATP stores chemical energy and makes it available to a

cell.

4.5: Cellular Respiration

Describe how the reactions of cellular respiration release chemical

energy.

Describe the general metabolic pathways of carbohydrate

metabolism.

69


4.6: Nucleic Acids and Protein Synthesis

Describe how DNA molecules store genetic information.

Describe how DNA molecules are replicated.

Explain how protein synthesis relies on genetic information.

Compare and contrast DNA and RNA.

Describe the steps of protein synthesis.

4.7: Changes in Genetic Information

Describe how genetic information can be altered.

Explain how a mutation may or may not affect an organism.

powerpoint to accompany hole’s human anatomy and ... 4.4: energy for metabolic reactions •...

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