unit 4 genetics ch. 12 dna & rna. griffith & transformation griffith injected mice with 4...

Unit 4 GeneticsUnit 4 Genetics

Ch. 12 DNA & RNACh. 12 DNA & RNA

Griffith & Transformation


Griffith injected mice with 4 different samples of bacteria

When injected separately, neither heat-killed (disease-causing bacteria), nor live, (harmless bacteria) killed the

mice

Griffith injected mice with 4 different samples of bacteria

When injected separately, neither heat-killed (disease-causing bacteria), nor live, (harmless bacteria) killed the

mice



The 2 types injected together, however, caused fatal pneumonia

From this experiment, biologists concluded (inferred) that genetic info. could be transferred from 1 bacterium to another

The 2 types injected together, however, caused fatal pneumonia

From this experiment, biologists concluded (inferred) that genetic info. could be transferred from 1 bacterium to another

Griffith’s ExperimentGriffith’s Experiment



Transformation - when 1 strain of bacteria is changed by a gene or genes from another strain of bacteria

Transformation - when 1 strain of bacteria is changed by a gene or genes from another strain of bacteria

Avery & DNAAvery & DNA

Avery & other scientists performed experiments to determine if transformation required just 1 particular molecule (of a gene)

Discovered that the nucleic acid, DNA, stores & transmits genetic info. from 1 generation of an organism to the next

Avery & other scientists performed experiments to determine if transformation required just 1 particular molecule (of a gene)

Discovered that the nucleic acid, DNA, stores & transmits genetic info. from 1 generation of an organism to the next

The Hershey-Chase Experiment


Studied viruses, nonliving particles smaller than a cell, that can infect living organisms

Bacteriophage - virus that infects bacteria

Studied viruses, nonliving particles smaller than a cell, that can infect living organisms

Bacteriophage - virus that infects bacteria



They performed experiments with a bacteriophage to determine its genetic material

They concluded that the genetic material of the bacteriophage was DNA & not protein

They performed experiments with a bacteriophage to determine its genetic material

They concluded that the genetic material of the bacteriophage was DNA & not protein

The Components & Structure of DNAThe Components & Structure of DNA

Genes were known to do 3 specific things: Carry info. from 1 generation to the next

Put that info. to work by determining heritable characteristics of organisms

Be easily copied, since all of a cell’s genetic info. is replicated every time a cell divides

Genes were known to do 3 specific things: Carry info. from 1 generation to the next

Put that info. to work by determining heritable characteristics of organisms

Be easily copied, since all of a cell’s genetic info. is replicated every time a cell divides


DNA is a long molecule made up of units called nucleotides

Nucleotides - made up of 3 parts: A sugar A phosphate group A nitrogenous base

DNA is a long molecule made up of units called nucleotides

Nucleotides - made up of 3 parts: A sugar A phosphate group A nitrogenous base


Watson & Crick developed the model of DNA, a double helix, where 2 strands were wound around each other

Watson & Crick developed the model of DNA, a double helix, where 2 strands were wound around each other


The 2 strands of DNA are held together by hydrogen bonds

Those bonds only link adenine (A) & thymine (T), & guanine (G) & cytosine (C)

Base-pairing rule - A - T, G - C

The 2 strands of DNA are held together by hydrogen bonds

Those bonds only link adenine (A) & thymine (T), & guanine (G) & cytosine (C)

Base-pairing rule - A - T, G - C

Structure of DNAStructure of DNA

DNA & ChromosomesDNA & Chromosomes

Most prokaryotes have a single circular DNA molecule in their cytoplasm

Most prokaryotes have a single circular DNA molecule in their cytoplasm


Eukaryotic DNA is located in the nucleus, in the form of a # of chromosomes

The chromosome # varies from 1 species to another

Eukaryotic DNA is located in the nucleus, in the form of a # of chromosomes

The chromosome # varies from 1 species to another


Eukaryotic chromosomes have both DNA & protein, packed tightly together to form chromatin

Chromatin - DNA that is tightly coiled around proteins (histones)

Eukaryotic chromosomes have both DNA & protein, packed tightly together to form chromatin

Chromatin - DNA that is tightly coiled around proteins (histones)


From largest to smallest, genetic information is arranged the following way: Chromosomes Genes (found on chromosomes) DNA (makes up genes)

From largest to smallest, genetic information is arranged the following way: Chromosomes Genes (found on chromosomes) DNA (makes up genes)

DNA ReplicationDNA Replication

Each strand of DNA could be used to make the other strand, they compliment each other

Replication - when a cell’s DNA is copied

Each strand of DNA could be used to make the other strand, they compliment each other

Replication - when a cell’s DNA is copied


During DNA replication, the DNA molecule separates into 2 strands, then produces 2 new complimentary strands following base pairing rules

Each strand of the double helix serves as a template, or model, for the new strand

During DNA replication, the DNA molecule separates into 2 strands, then produces 2 new complimentary strands following base pairing rules

Each strand of the double helix serves as a template, or model, for the new strand


DNA polymerase - enzyme that joins individual nucleotides to produce a DNA molecule

It also proofreads each new DNA strand, to help prevent errors in copying the DNA

DNA polymerase - enzyme that joins individual nucleotides to produce a DNA molecule

It also proofreads each new DNA strand, to help prevent errors in copying the DNA

RNA & Protein Synthesis

RNA & Protein Synthesis

Genes - coded DNA instruc. that control the production of proteins within the cell

The 1st step in decoding the genetic messages is to copy part of the nucleotide sequence from DNA into RNA

Genes - coded DNA instruc. that control the production of proteins within the cell

The 1st step in decoding the genetic messages is to copy part of the nucleotide sequence from DNA into RNA

The Structure of RNAThe Structure of RNA

There are 3 main differences between RNA & DNA: The sugar is a ribose, instead of deoxyribose

RNA is single-stranded RNA contains the nitrogenous base uracil (U) instead of thymine (T)

There are 3 main differences between RNA & DNA: The sugar is a ribose, instead of deoxyribose

RNA is single-stranded RNA contains the nitrogenous base uracil (U) instead of thymine (T)

Types of RNATypes of RNA

There are 3 main types of RNA: Messenger RNA Ribosomal RNA Transfer RNA

There are 3 main types of RNA: Messenger RNA Ribosomal RNA Transfer RNA


Messenger RNA - (mRNA) - RNA molecules that carry copies of instructions for assembling amino acids into proteins They serve as “messengers” from DNA to the rest of the cell

Messenger RNA - (mRNA) - RNA molecules that carry copies of instructions for assembling amino acids into proteins They serve as “messengers” from DNA to the rest of the cell


Ribosomal RNA - (rRNA) - form of RNA that combines with proteins to make a ribosome

Ribosomal RNA - (rRNA) - form of RNA that combines with proteins to make a ribosome


Transfer RNA - (tRNA) - RNA molecule that transfers each amino acid to the ribosome as it is specified by coded messages in mRNA

Transfer RNA - (tRNA) - RNA molecule that transfers each amino acid to the ribosome as it is specified by coded messages in mRNA


Transcription - process of producing RNA molecules by copying part of the nucleotide sequence of DNA into a complimentary sequence of RNA

RNA polymerase - enzyme that works similarly to DNA polymerase

Transcription - process of producing RNA molecules by copying part of the nucleotide sequence of DNA into a complimentary sequence of RNA

RNA polymerase - enzyme that works similarly to DNA polymerase


During transcription, RNA polymerase binds to DNA & separates the DNA strands

RNA polymerase then uses 1 strand of DNA as a template to assemble nucleotides into a strand of RNA

During transcription, RNA polymerase binds to DNA & separates the DNA strands

RNA polymerase then uses 1 strand of DNA as a template to assemble nucleotides into a strand of RNA

TranscriptionTranscription

The Genetic CodeThe Genetic Code

Proteins are made by joining amino acids into long chains - polypeptides

Each polypeptide has a combination of any 20 different amino acids

Proteins are made by joining amino acids into long chains - polypeptides

Each polypeptide has a combination of any 20 different amino acids


Codon - 3 consecutive nucleotides that specify a single amino acid to be added to the polypeptide

Codon - 3 consecutive nucleotides that specify a single amino acid to be added to the polypeptide


For ex.: UCGCACGGU Read 3 at a time:

UCG-CAC-GGU Which represents amino acids:

Serine-Histidine-Glycine

For ex.: UCGCACGGU Read 3 at a time:

UCG-CAC-GGU Which represents amino acids:

Serine-Histidine-Glycine

TranslationTranslation

Translation - (protein synthesis) -decoding an mRNA message into a polypeptide chain (protein)

It takes place on ribosomes Before translation occurs, mRNA is transcribed (re-written) from DNA in the nucleus & released in the cytoplasm

Translation - (protein synthesis) -decoding an mRNA message into a polypeptide chain (protein)

It takes place on ribosomes Before translation occurs, mRNA is transcribed (re-written) from DNA in the nucleus & released in the cytoplasm


Translation then begins when an mRNA molecule in the cytoplasm attaches to a ribosome

As each codon of mRNA moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA

Translation then begins when an mRNA molecule in the cytoplasm attaches to a ribosome

As each codon of mRNA moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA


Each tRNA molecule has an anticodon - 3 nitrogenous bases that are complimentary to 1 mRNA codon

The ribosome attaches 1 amino acid to another, forming the polypeptide chain, until it reaches the “stop” codon

Each tRNA molecule has an anticodon - 3 nitrogenous bases that are complimentary to 1 mRNA codon

The ribosome attaches 1 amino acid to another, forming the polypeptide chain, until it reaches the “stop” codon


After the amino acid is attached, the tRNA molecule that brought it into the ribosome, is released back into the cytoplasm

The result is a protein

After the amino acid is attached, the tRNA molecule that brought it into the ribosome, is released back into the cytoplasm

The result is a protein

Summary: Role of RNA & DNA

Summary: Role of RNA & DNA

Start with a single strand of DNA

That DNA is transcribed into RNA The RNA is separated into codons The codons code for amino acids, which form a polypeptide chain

Start with a single strand of DNA

That DNA is transcribed into RNA The RNA is separated into codons The codons code for amino acids, which form a polypeptide chain

Genes & ProteinsGenes & Proteins

Many proteins are enzymes that catalyze & regulate chemical reactions

Genes for proteins can regulate the rate & pattern of growth throughout an organism

Proteins are microscopic tools that are designed to build or operate a living cell

Many proteins are enzymes that catalyze & regulate chemical reactions

Genes for proteins can regulate the rate & pattern of growth throughout an organism

Proteins are microscopic tools that are designed to build or operate a living cell

MutationsMutations

Mutations - a mistake in the DNA base sequence, may occur during copying the DNA

Changes in the genetic material

Mutations - a mistake in the DNA base sequence, may occur during copying the DNA

Changes in the genetic material

Kinds of MutationsKinds of Mutations

Gene mutations are changes in a single gene

Chromosomal mutations are changes in the whole chromosome

Gene mutations are changes in a single gene

Chromosomal mutations are changes in the whole chromosome

Gene MutationsGene Mutations

Point mutations - change in 1 or a few nucleotides, they occur at a single point in the DNA sequence

Frameshift mutations - adding or deleting a nucleotide, shifts the “reading frame” of the genetic message

Point mutations - change in 1 or a few nucleotides, they occur at a single point in the DNA sequence

Frameshift mutations - adding or deleting a nucleotide, shifts the “reading frame” of the genetic message

Chromosomal MutationsChromosomal Mutations

There are 4 types of chromosomal mutations: deletions, duplications, inversions, & translocations

Deletions involve the loss of all or part of a chromosome

Duplications produce extra copies of parts of a chromosome

There are 4 types of chromosomal mutations: deletions, duplications, inversions, & translocations

Deletions involve the loss of all or part of a chromosome

Duplications produce extra copies of parts of a chromosome

Chromosomal MutationsChromosomal Mutations

Inversions reverse the direction of parts of chromosomes

Translocations occur when part of one chromosome

breaks off & attaches to another

Inversions reverse the direction of parts of chromosomes

Translocations occur when part of one chromosome

breaks off & attaches to another

Significance of Mutations

Significance of Mutations

Mutations cause changes in protein structure or gene activity

They are the cause of many genetic disorders

Some are associated with many types of cancer

Mutations cause changes in protein structure or gene activity

They are the cause of many genetic disorders

Some are associated with many types of cancer

Eukaryotic Gene Regulation

Eukaryotic Gene Regulation

Genes that code for liver enzymes are not expressed in nerve cells

Cell specialization requires genetic specialization, but all cells in a multicellular organism carry the complete genetic code in their nucleus

Genes that code for liver enzymes are not expressed in nerve cells

Cell specialization requires genetic specialization, but all cells in a multicellular organism carry the complete genetic code in their nucleus

unit 4 genetics ch. 12 dna & rna. griffith & transformation griffith injected mice with 4...

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