AP Biology chapter 6

Who made the first model of DNA?

Watson and Crick

Who captured the first image of DNA

Rosalind Franklin

What are the building blocks of DNA?

phosphorus base, deoxyribose, and nitrogen bases

What are the 5 nitrogen bases?

Guanine, Thymine, Adenine, Cytosine, and Uracil

What base does Uracil substitute for in RNA?

Thymine

What are purines?

Large and have double rings

Guanine and Adenine

What are pyrimidines?

Small and have 1 ring

Cytosine, Thymine, and Uracil

What does the helicase enzyme do?

it “unzips” the double helix

What enzyme prevents supercooling?

Topoisomerase

What enzyme adds a RNA primer?

RNA primase

What adds DNA base pairs first?

DNA polymerase III in the 5’ to 3’ direction

What is the strand that can be synthesized continuously called?

Leading strand

What is the strand that has to be made in fragments called?

Lagging strand

What are the DNA fragments on the lagging strand called?

Okazaki fragments

What enzyme removes RNA primers?

Exonuclease

What replaces the RNA primers with DNA?

DNA polymerase I

What seals the gaps in-between the fragments of DNA?

DNA ligase

What are telomeres?

They are the ends of the chromosomes

Do telomeres code for genes?

no they don’t code for genes

What are the telomeres job?

They make sure genes don’t get deleted during replication.

What enzyme keeps telomeres long

Telomerase

Who discovered that somatic cells don’t have telomerase?

Elizabeth Blackburn

What is the effect of having no telomerase in somatic cells?

It causes us to age.

What is the process of proofreading?

It is when DNA polymerase checks each base for mistakes before adding the next base.

What is a mismatch repair?

It is when an enzyme recognizes a wrong base combination and corrects it.

What process cuts out and replaces the wrong base?

Nucleotide excision

What are thymine dimers and what are they a result of?

They are covalent bonds between two adjacent thymines

UV light and no repairs of DNA mutations

What are induced mutations

they are a result of external factors

what mutations are a result of natural body reactions

spontaneous mutations

what are silent mutations

They are mutations that aren’t expressed

What are mutations that affect a single base pair called?

Point mutations

What are transition mutation

it is when a purine (or pyrimidine) is replaced by another purine (or pyrimidine)

What mutations involve a purine replacing a pyrimidine or vice versa?

Transversion

what is the central dogma?

Transcription makes pre-mRNA, which makes mRNA, which makes amino acids, which makes proteins

What is a codon

it is a sequence of 3 base pairs that code for a single amino acid

Can multiple codons code for the same amino acid?

They can

it means genetic code is degenerate

How many codons are there

64

Out of the 64 codons how many are stop codons?

3

What is the transcription bubble

it is where the DNA unwinds

what are transcription factors

they help find the RNA polymerase that matches the promoter

Polymerase I

rRNA

Polymerase II

pre-mRNA

Polymerase III

5srRNA, tRNA, and other small RNA

Where does the RNA polymerase bind

TATA box

what positions the DNA in the polymerase active site

preinitiation complex

prokaryotic ribosomes

30s & 50s =70s

eukaryotic ribosomes

40s & 60s =80s

What refills 1 out of the 20 amino acids for tRNA

aminoacyl tRNA sythetase

what is gene expression

it is the process of turning genes on and off

what is the lac operon

it is a catabolic reaction and an inducible control

it is turned on by the presence of lactose

what is the trp operon

it is a repressible control

it is only turned of when there is too much trp in the cell

What proteins stop transcription

Repressor proteins

What proteins increase transcription rates

activator proteins

What does DNA wrap around

histone proteins

What does adding a methyl group do? What is it called?

Tightens DNA around the histone

methylation

What does adding an acetyl group do? What is this called?

it loosens the DNA around the histone

acetylation

What does DNA bending protein do

brings enhancers closer to the transcription factors by bending the DNA

What it is called when transcription factors bind to the promoter upstream of the gene?

Cis- acting element