Cell Division and Gene Expression Cell Division and Gene Expression

• The Need for Cell Reproduction

- The Nature of Chromosomes

- The Cell Cycle

- Mitosis and Cytokinesis

- Cancer Cells: Abnormal Cell Cycle

• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein

- Transcription by RNA Polymerase (DNA gene --> mRNA)

- The Three Types of RNA

- Translation by Ribosome

Transcription

• RNA polymerase

• Enzyme that oversees synthesis of mRNA

• Unwinds DNA template

• Adds complementary RNA nucleotides on DNA template and joins them together

• Stops when it reaches termination signal

• mRNA pulls off the DNA template, is further processed by enzymes, and enters cytosol

Transcription: From DNA to RNA• In transcription,

Genetic information is transferred from DNA to RNA (an RNA molecule is transcribed from a DNA template)

Transcription

GCAAATGCTGGCCGGAATCTAGGACTGC

CGTTTACGA CCGGCCTTAGATCCTGACG

CGTTTACGA CCGGCCTTAGATCCTGACG

GCAAATGCTGGCCGGAATCTAGGACTGC

U C

G U A A A G C

RNA PolymeraseMakes a complementary copy of RNA from DNA

Cell Division and Gene Expression Cell Division and Gene Expression

• The Need for Cell Reproduction

- The Nature of Chromosomes

- The Cell Cycle

- Mitosis and Cytokinesis

- Cancer Cells: Abnormal Cell Cycle

• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein

- Transcription by RNA Polymerase

- The Three Types of RNA

- Translation by Ribosome

=

3 Types of RNA – Each With a Different JobMessenger RNA (mRNA)

Carries copy of gene informationto the ribosome to make protein

anticodon

Ribosomal RNA (rRNA)

Part of the structure ofthe ribosome; key component in aminoacid linking machinery

CUG

C U G

Transfer RNA (tRNA)

Carries amino acids to the ribosome for linking; identified by anticodon “sign”

Figure 10.17

Anatomy of a Messenger RNA

Leader

Trailer

Cell Division and Gene Expression Cell Division and Gene Expression

• The Need for Cell Reproduction

- The Nature of Chromosomes

- The Cell Cycle

- Mitosis and Cytokinesis

- Cancer Cells: Abnormal Cell Cycle

• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein

- Transcription by RNA Polymerase

- The Three Types of RNA

- Translation by Ribosome

- The Genetic Code

How Gene Instructions are Communicated

mRNA Codon Dictionary of the Genetic Code

SECOND BASE

UUG

UUA

UUC

UUUPhe

Leu

CUG

CUA

CUC

CUU

Leu

AUA

AUC

AUU

Ile

GUG

GUA

GUC

GUU

Val

UCG

UCA

UCC

UCU

Ser

CCG

CCA

CCC

CCU

Pro

ACG

ACA

ACC

ACU

Thr

GCG

GCA

GCC

GCU

Ala

UAC

UAUTyr

CAG

CAA

CAC

CAUHis

Gln

AAG

AAA

AAC

AAUAsn

Lys

GAG

GAA

GAC

GAUAsp

Glu

UGC

UGUCys

Trp

CGG

CGA

CGC

CGU

Arg

AGG

AGA

AGC

AGUSer

Arg

GGG

GGA

GGC

GGU

Gly

UAA Stop UGA Stop

AUGMet orStart

UAG Stop UGG

U C A G

G

A

C

U

G

A

C

U

G

A

C

U

G

A

C

U

U

C

A

G

DNA template strand:

CGTTTACGACCGGCCTTAGATCCTGACG

Central Dogma: DNARNAProtein

mRNA: GCAAAUGCUGGCCGGAAUCUAGGACUGC

Transcription by RNA polymerase

Translation by ribosome

Protein: Met -

Leu -Ala -

Gly -Ile

Translation

Cell Division and Gene Expression Cell Division and Gene Expression• The Need for Cell Reproduction

- The Nature of Chromosomes

- The Cell Cycle

- Mitosis and Cytokinesis

- Cancer Cells: Abnormal Cell Cycle

• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein

- Transcription by RNA Polymerase

- The Three Types of RNA

- Translation by Ribosome

-The Genetic Code

-The Three Steps of Translation: Initiation, Elongation, & Termination

Simplified Diagram of a Ribosome

Transcription has 3 parts:1. Initiation, where the ribosome assembles with

mRNA2. Elongation, where the protein chain grows3. Termination, where the new protein is released

Translation

mRNA

tRNA

Growing amino acid chain (polypeptide)

E P A

Initiation

Elongation

Termination

Figure 10.10

The Big Picture Regarding DNA->RNA -> Protein

Cell Division and Gene Expression Cell Division and Gene Expression

• The Need for Cell Reproduction

- The Nature of Chromosomes

- The Cell Cycle

- Mitosis and Cytokinesis

- Cancer Cells: Abnormal Cell Cycle

• The Expression of Genes as Proteins: DNA gene --> RNA --> Protein

- Transcription by RNA Polymerase

- The Three Types of RNA

- Translation by Ribosome