Top Banner
29

Replication DnA Dna

Dec 31, 2015

Download

Documents

Marshall Green

Replication DnA Dna. We lose from 30,000-40,000 cells/day……these need to get replaced Before a cell duplicates, it makes an exact copy of its DNA for new cell Double helix “unzips” through an enzyme ( helicase ) that breaks H bonds - PowerPoint PPT Presentation
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Replication DnA Dna
Page 2: Replication DnA Dna

We lose from 30,000-40,000 cells/day……these need to get replaced

Before a cell duplicates, it makes an exact copy of its DNA for new cell Double helix “unzips” through an enzyme

(helicase) that breaks H bonds DNA polymerase attaches nucleotides to

DNA strand to form complementary strands

Page 3: Replication DnA Dna
Page 4: Replication DnA Dna
Page 5: Replication DnA Dna
Page 6: Replication DnA Dna

DNA never leaves the nucleus, is protected RNA is a copy of DNA that goes out of

nucleus to give cell instructions to make proteins

3 Main Differences between RNA to DNA Single stranded, smaller Contains ribose sugar Contains uracil in place of thymine

Ribose Sugar

Adenine: AUracil: UGuanine: GCytosine: C

Page 7: Replication DnA Dna

DNA unzips at site of desired gene at promoters (specific base sequence signal for start)

RNA polymerase creates a complimentary strand of gene with RNA nucleotides

mRNA leaves nucleus to ribosome for protein synthesis

Page 8: Replication DnA Dna

Sometimes in the RNA copy, there are some portions that don’t code for the protein (introns)

Introns get discarded and remaining portions (exons) of RNA get spliced back together.

Page 9: Replication DnA Dna

Transcription happens in the nucleus. An RNA copy of a gene is made.

Then the mRNA that has been made moves out of the nucleus into the cytoplasm

Once in the cytoplasm, the mRNA is used to make a protein

Cytoplasm of cell

Nucleus

DNAmRNA

mRNA

Page 10: Replication DnA Dna

Messenger RNA (mRNA)- carry info on polypeptide synthesis from nucleus to ribosomes

Ribosomal RNA (rRNA)- make up subunits that make ribosomes

Transfer RNA (tRNA)- bring amino acids to the ribosome and matches them to coded mRNA message

Page 11: Replication DnA Dna

Table 14.2Types of RNA

Type of RNA Functions in Function

Messenger RNA(mRNA)

Nucleus, migratesto ribosomesin cytoplasm

Carries DNA sequenceinformation to ribosomes

Transfer RNA(tRNA)

Cytoplasm Provides linkage between mRNAand amino acids;transfers aminoacids to ribosomes

Ribosomal RNA(rRNA)

Cytoplasm Structural component of ribosomes

Page 12: Replication DnA Dna
Page 13: Replication DnA Dna

*Ribosome binds to mRNA in cytoplasm

•Genetic code is read in words that are 3 letters long called CODONS

• Each codon codes for an AMINO ACID

Page 14: Replication DnA Dna

U C A G

U

C

A

G

GACU

GACU

GACU

GACU

UUUUUCUUAUUG

CUUCUCCUACUG

AUUAUCAUAAUG

GUUGUCGUAGUG

phe

leu

leu

ile

met (start)

val

UCUUCCUCAUCG

CCUCCCCCACCG

ACUACCACAACG

GCUGCCGCAGCG

ser

pro

thr

ala

UAUUACUAAUAG

CAUCACCAACAG

AAUAAC

AAGAAA

GAUGACGAAGAG

tyr

stopstop

his

gln

asn

lys

asp

glu

UGUUGCUGAUGG

CGUCGCCGACGG

AGUAGCAGAAGG

GGUGGCGGAGGG

cys

stoptrp

arg

ser

arg

gly

Firs

t B

ase

Third

Base

Second Base

Virtually all organisms share the same genetic code “unity of life”

mRNA AMINO ACID CHART

Page 15: Replication DnA Dna

As each codon passes through ribosome, tRNA brings the proper amino acids to ribosome to build a polypeptide

Anticodon is used to base pair with mRNA codons

Page 16: Replication DnA Dna
Page 17: Replication DnA Dna
Page 18: Replication DnA Dna

The polypeptide chain continues to grow until it reaches a “stop” codon on mRNA

Ribosome releases new polypeptide and mRNA, completing translation

Page 19: Replication DnA Dna
Page 20: Replication DnA Dna
Page 21: Replication DnA Dna
Page 22: Replication DnA Dna
Page 23: Replication DnA Dna

TRANSLATION

Figure 10.8B

Startcodon

RNA

Transcribed strand

StopcodonTranslation

Transcription

DNA

Polypeptide

CODONS

Page 24: Replication DnA Dna
Page 25: Replication DnA Dna

Figure 10.16A

Normal hemoglobin DNA

mRNA

Normal hemoglobin

Glu

Mutant hemoglobin DNA

mRNA

Sickle-cell hemoglobin

Val

Page 26: Replication DnA Dna

Mutations are changes in the DNA base sequence caused by errors in DNA replication or by

mutagens (chemical/physical agents) Point mutation involves change in one or

a few nucleotides

Page 27: Replication DnA Dna

Types of mutations

Figure 10.16B

mRNA

NORMAL GENE

BASE SUBSTITUTION

BASE DELETION or INSERTION

Protein Met Lys Phe Gly Ala

Met Lys Phe Ser Ala

Met Lys Leu Ala His

Missing

*FrameshiftMutation (more serious)

Page 28: Replication DnA Dna

FRAMESHIFT: Shifts entire sequence over, can result in defective protein

POINT Mutation- can produce defective protein

Page 29: Replication DnA Dna

TAC GCC TGG AAA

AUG CGG ACC UUU

MET ARG THR PHE

Silent mutation (substitution) because there is more than one codon for each AA