lecture 01 slides

7/23/2019 Lecture 01 Slides

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The Human Body

food energy conversion efficiency:30% (cars: 20%)

signal transduction: >100 m/sec

skeleton more stress resistant andflexible than steel, but lighter

lung surface area is similar to half

of a tennis court

heart beats about 3 billion times

length of circulatory system is60,000 miles, blood travels about12,000 miles a day

more than 70% of us is H2O

The Human Body, Part II

collection of ~ 1014cells(Comparison: World population is

~7 x 109)

~200 different cell types

your brain has ~1011nerve cells

~2 x 106blood cells are born per

second

your GI tract contains many

bacteria


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Cells are the Basic Building Block

of All Life

E. coli

2 m

nerve cell

4 - 100 m body

up to 3 ft long

Ostrich egg

6 in by 5 in

3 lbs

The Cell

structural and functional unit of life

controlled environment separated from theoutside by a cell membrane

self-renewing; information passed to offspring

self-contained

uses energy organotrophic: organic compounds

phototrophic: light

lithothrophic: inorganic compounds

optional oxygen requirement (aerobe/anaerobe)

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All cells employ similar biological mechanisms.


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All Cells Use Similar

Polymeric Building BlocksPolymeric

Molecule

Monomeric

ComponentFunction

Lipid fatty acid membrane

DNAdeoxy-ribonucleotide

information storage,inheritance

RNA ribonucleotideinformation storage,biological function

Protein amino acid

biological function,

cellular structure

Oligosaccharides(sugars)

mono-saccharides

cellular structure,energy storage

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Definitions

Metabolism:Set of chemical reactions occurring in a living

organism in order to maintain life.

Anabolism:

Set of chemical reactions that build cellular order.

Usually requires energy input.

Catabolism:Set of chemical reactions that break down cellularmacromolecules. Usually releases energy as heat.

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Condensation / Hydrolysis

A OH + B OH A O B + H2O

combine two molecules through ether linkage

forward reaction: condensation reverse reaction: hydrolysis

key to building polymers from monomers

condensation

hydrolysis

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1. Lipids & Membranes

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Lipids:

amphipathic: hydrophilic head

hydrophobic tails

built from fatty acids by

condensation reactions

self-assemble into membranes

Membranes:

impermeable to most

molecules

separate liquid spaces cell and environment

compartments within cell

(organelles)

membrane

head

tails


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consist of long

a condensation cytidine (C)

thymidine (T)

two c run in

form a

all DNA in a

an uninterrupteda chromosome

a geneis a

consist of long chains of deoxyribonucleotides, fused by

a condensation reaction adenosine (A)

guanosine (G)

two complementary strands run in opposite direction

form a double-helix

all DNA in a cell is its genome

an uninterrupted run of DNA isa chromosome

a geneis a portion of the DNAon a chromosome

2. Deoxyribonucleic Acid (DNA)

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unicellular organisms have mostly small genomes, multicellular large ones can have anywhere between 1 and 100s of chromosomes each chromosome may be present in one or multiple copies (ploidy)

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Human Genome

3 x109nucleotides

23 chromosomes 22 autosomes

1 sex chromosome

diploid: 2 copies of each chr.

20,000 25,000 genes

Human Genome Project DNA is same in each cell of

one individual

(except in B and T cells)


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DNA and genes defineattributes of each being

variation

mutation

passed from generation

to generation

biological memory

safeguarded

used to make working

copy (RNA)15

!



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linear strand of ribonucleotideslinked by condensation reactions

adenosine guanosine cytidine uridine

RNA differs from DNA by: one extra OH group uridine replaces thymidine

highly flexible folds into myriad shapes common structures:

stems: double-stranded loops: single-stranded

3. Ribonucleic Acid (RNA)

tRNA

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3. Ribonucleic Acid (RNA)

different classes of RNAwith different function: mRNA: information carrier

rRNA: ribosome

tRNA: amino acid carrier

siRNA: regulator

etc.

some RNAs have catalytic

function (eg, ribosome)ribosome

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linear chain of

amino acids (peptide)

20 different amino acids

short (28 aas, Insulin) tolong (27,000 aas, Titin)

fused together using a

condensation reaction

flexible!

4. Proteins

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Function

catalytic (enzymes): increase speed of

biochemical reactions

functional: bind other molecules

regulate other molecules

structural: provide rigid backbone for

cells (eg., actin, keratin)

4. Proteins

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condensation reaction: combine monomers

release H2O

common disaccharides: sucrose (table sugar):

glucose and fructose

lactose(milk sugar):

galactose and glucose

common glucose

polysaccharides: cellulose (linear)

glycogen(branched)

5. Polysaccharides (Sugars)

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Polysaccharides in Biology

attached to proteins and lipids(glycoproteins and glycolipids)

to modify function

glycocalyx: coat of sugars

surrounding a cell

polysaccharide function: energy storage (glycogen)

distinguish self from foreign(immunology; blood types)

structure of plant cell wall

(cellulose)

insect exoskeleton (chitin)

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All Cells Use Similar

Molecular Building Blocks

MoleculeMonomeric

ComponentFunction

Lipid fatty acid membrane

DNAdeoxy-ribonucleotide

information storage,inheritance

RNA ribonucleotideinformation storage,biological function

Protein amino acid

biological function,

cellular structure

Oligosaccharides(sugars)

mono-saccharides

cellular structure,energy storage

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Information Flow inside a Cell

DNA RNA Protein

Transcription(RNA Synthesis)RNA Polymerase

Translation(Protein Synthesis)

Ribosome


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Domains of the Living World

Prokaryotes no nucleus generally unicellular

Eukaryotes DNA in a separatecompartment (nucleus)

presence of organelles

can be multicellular 36(c/k)aryote: Greek for nucleus

Bacteria

abundant and diverse

microscopic (


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Archaea

similar to bacteria, but

independent history different biology

unicellular

no organelles or nucleus!

energy sources:

organic compounds and light inorganics (lithotrophic)

may live in extreme environ-

ments (extremophiles)38

Eukaryotes

uni- or multicellular

short to long life cycles

size: 10 m to meters

have nucleus

have organelles

complex, large genomes

functional compartmentalization within a cell (organelles)

within an organism, if multicellular

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Structure of a Prokaryote

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Structure of a Eukaryote

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Two General Points

key components are modular cells form the basic biological unit

small number of building blocks arranged in a specific

order along a chain for infinite variability of structure

(RNA, protein) or maximizing information content(DNA, RNA)

advantage: only need one set of enzymes to make or

break down one polymer (condensation/hydrolysis)

membrane is absolutely essential for life build-up concentration gradients

restrict transfer of molecules into and out of cells

sequester harmful reactions into own compartment42

Biological Mechanisms

are Conserved

all living creatures consist of cells

all cells have the same main molecular

components and same basic machinery:

lipids

protein

oligosaccharides

therefore, studying model organisms can answer

questions about human biology E. coli

yeast

worms

DNA

RNA

fruit fly

zebrafish

mice43

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