exam 4

Nucleic acid

DNA and RNA polymers

Polynucleotide

A polymer consisting of many nucleotide monomers in a chain; nucleotides can be those of DNA or RNA

Phosphate group

Functional group in DNA

Phosphodiester bond

The bond that links the nucleotides in DNA or RNA

5'

Head of DNA

3'

Tail end of DNA

DNA

Controls synthesis of mRNA

2

A and T have _____ hydrogen bonds

3

C and G have _____ hydrogen bonds

Transcription

Synthesis of an RNA molecule from a DNA template

Translation

Process by which mRNA is decoded and a protein is produced

S phase

Phase where DNA is replicated

Semiconservative replication

Double stranded parent DNA unwinds into 2 single strands which act as templates to synthesize a new daughter strand

Erwin Chargaff rule

A pairs to T, C pairs to G, equal numbers of one to its pair

Origin of replication

Special site where replication begins, where two parental strands of DNA are separated

Replication bubble

Segment of a DNA molecule that is unwinding and undergoing replication, bidirectional

Helicase

Enzyme that unwinds the double helix at replication forks

Single strand binding proteins (SSBs)

Bind and stabilize the single strand of DNA left behind from helicases to make sure it doesn't rebind backwards

Topoisomerase

Breaks and rejoins the DNA strands to relieve built-up strain of helicase unzipping

Primase

Enzyme that lays down a primer on the parental DNA strand

Primer

Short RNA segment that acts as an attachment point for enzyme DNA Polymerase III

DNA Polymerase III

Catalyzes DNA synthesis and requires a template with all 4 dNTPs

dNTP

Deoxyribonucleoside triphosphate

Nucleoside

Base + sugar

Adenine

dATP

Guanine

dGTP

Cytosine

dCTP

Thymine

dTTP

Phosphate group

Functional group attached to the 5th carbon of DNA (5')

Hydroxyl group

Functional group attached to the 3rd carbon of DNA (3')

5' to 3'

Direction of DNA synthesis on the new daughter strand

Primer, template strand

Polymerases need these 2 things to synthesize DNA

Okazaki fragments

Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand

DNA Polymerase I

Removes the RNA primers and filled the holes left with DNA

DNA Ligase

Joins the DNA fragments in the lagging strand

Exonuclease activity

The ability of DNA Pol III to move backwards to remove a nucleotide from the end of a DNA strand in DNA replication

Glycosylase

Repair enzyme that remove the wrong base or error

Endonuclease

Enzyme that makes the cut in DNA repair

Mismatch repair

Repair when enzymes correct errors in base pairing

Base excision repair

Repair when enzymes repair damage to a single nitrogenous base

AP site

A position in DNA where there is no base attached to the sugar of the backbone

DNA polymerase

Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule, has 5' to 3' exonuclease activity

Nucleotide excision repair

Repair. needed when a few of the DNA nucleotides in a stretch are damaged

Gene expression

Transcription and translation

Ligase

An enzyme that connects two fragments of DNA to make a single fragment

mRNA

Creates proteins through translation

rRNA

Creates ribosomes

tRNA

Molecule that carries a specific amino acid to the ribosome to make protein

miRNA

Plays a role in RNA silencing

snRNA

Plays a role in RNA interference

Coupled

In prokaryotes, transcription and translation are _____

Pribnow box

Consensus sequence in prokaryotes (name)

TATAAT

Pribnow box sequence

Terminator region

The nucleotide sequence at the end of a gene that signals the end of transcription in prokaryotes

Chromatin remodeling

Uncoiling of chromatin

Transcription factors

Collection of proteins that mediate the binding of RNA polymerase and the initiation of transcription

TATA box

Consensus sequence for eukaryotes (name)

TATATA

TATA box sequence

Consensus sequence

Where transcription is initiated

40

While moving along DNA, the RNA polymerase unwinds the double helix and adds _____ nucleotides per second

Exhausted

Transcription ends in eukaryotes when it is _____

Eukaryotes

Processing and editing of DNA occurs in _____

Pre-mRNA

Form of mRNA that contains both introns and exons; before editing and processing

Nucleotide cap

During RNA processing, the 5' end receives a(n) _____

Poly-A tail

During RNA processing, the 3' end receives a(n) _____

Introns

Noncoding segments of nucleic acid that lie between coding sequences

Exons

Coding segments of eukaryotic DNA that are not removed

DNA splicing

Process of removing introns and joining exons

Spliceosome

Enzyme that carries out DNA splicing

Substitution

Editing when individual nucleotide bases are altered

Insertion/deletion

Editing when nucleotides are added/deleted from the total number of bases

UAA, UGA, UAG

Stop codons for translation

AUG

Start codon for translation

Methionine

AUG codes for this amino acid

80

tRNA molecule has a single RNA strand about _____ nucleotides long

Anticodon

tRNA has an amino acid on one end and a(n) _____ on the other

A site

Holds the tRNA carrying the next amino acid to be added to the chain

P site

Holds the tRNA carrying the growing polypeptide chain

E site

Where discharged tRNAs leave the ribosome

3

Protein collagen is made of _____ polypeptides

4

Protein hemoglobin is made of _____ polypeptides

Carboxyl and amino

2 functional groups in amino acids

H2O

Stop codons code for this molecule in translation

Single-base pair substitution

Mutation where a base is substituted for something else

Deletion or insertion

Mutation where one or more base pairs is deleted or inserted

Somatic

Mutations that occur in any cell except for germ cells and gametes, not heritable

Germ-line

Mutations that occur in gametes and germ cells, heritable

Spontaneous

Mutations that occur naturally and randomly, usually linked to normal biological or chemical processes in the organism

Free radicals

Unstable molecules that can cause spontaneous mutations

O atom

Example of a free radical

Induced

Mutations that result from the influence of an extraneous factor, either natural or artificial

Point mutation

Chemical changes in just one base pair of a gene

Transition

Base substitution in which a purine replaces a purine or a pyrimidine replaces a pyrimidine

Transversion

Base substitution in which a purine replaces a pyrimidine or a pyrimidine replaces a purine

A and G

Purines

C, T, U

Pyrimidines (alphabetical order)

Frameshift mutation

Mutation that involves the insertion or deletion of a nucleotide in the DNA sequence, shifts the reading frame

Silent

Mutation that has no effect on the amino acid produced due to redundancy in genetic code

Missense

Mutation that still codes for an amino acid, just not the right one

Sickle cell

Example of a missense mutation