Biology Unit 8

What does DNA stand for?

Deoxyribose acid

What is a nucleotide? Example?

a building block, ex: DNA or RNA

What are the three components of a nucleotide?

phosphate, sugar, base

What makes the 4 DNA nucleotides different?

they have different nitrogenous bases

What is Chargaffs rule?

A pairs with T and C pairs with G.

What is the basic shape of DNA?

double helix (twisted ladder)

What type of bonds hold the backbone of DNA together? What part is the backbone?

covelent bonds, the backbone is the sugar and phosphate

What type of bonds holds the 2 strands (bases) together?

hydrogen

What are the four main enzymes in order in DNA replication?

Helicase, Primase, DNA polymerase, ligase

What does Helicase do? Which step is it in?

unwinds/unzips DNA, it is first

What does Primase do? Which step is it in?

Primes DNA strand (prepares for next step), it is second

What does DNA polymerase do? Which step is it in?

makes new DNA strand by attaching nucleotides and it is step 3

What does Ligase do? Which step is it in?

glues pieces together to complete strand, step 4

How is DNA replication so fast?

it happens at a lot of different origins at once

What does semi conservative mean in the context of DNA replication?

each new DNA molecule has 1 original strand and 1 new strand

Location, Purpose, Result: Replication

Nucleus, Copies DNA. 2 identical DNA

Location, Purpose, Result: Transcription

Nucleus, turns DNA into RNA, mRNA

Location, Purpose, Result: Translation

Ribosome, RNA to Protein, Protein

Feature	DNA	RNA
Sugar
Strands
Bases
Shape

Feature	DNA	RNA
Sugar	Deoxyribose	Ribose
Strands	Double	Single
Bases	ATCG	AUCG
Shape	Double Helix	single strand

what are the three tyoes of RNA

mRNA, tRNA, rRNA

what is the function of mRNA

carries genetic code from DNA

what is the function of tRNA

brings amino acids to ribosome

what is the function of rRNA

makes up ribosome and helps build protein

What is a mutation?

a change in the DNA sequence

When does mutation occur?

during DNA replication or enviormental factors

3 types of point mutations and what they do

Substitution: Change one base for another

Insertion: Put a new base in the code

Deletion: Delete a base from the code

What are the three effects of mutations?

Silent: codes for the same amino acid; protein is unaffected

Missense: changes the amino acid; protein is impaired or nonfunctional

Nonsense: early stop codons; protein is not assembled completely

what is a frameshift mutation?

shifts every nucleotide out of place

what are the two types of frameshfits mutations?

insertion=adds a nucleotide, desertion=removes nucleotide

What could happen if a cell doesn’t have helicase?

the cell could not go through mitosis

what is the order of enzymes in DNA replication?

helicase, primase, DNA polymerase, ligase

what enzyme preforms transcripition?

RNA polymerase

What is the name for a three nucleotide sequence of mRNA that codes for an amino acid?

codon