Biology Exam 2

Building blocks of DNA

sugar, phosphate, base

How are nucleotides bonded

covalent phophodiester bonds

What reaction joins nucleotides

condensation, lose water

How is the double helix held together

hydrogen bond

Purine

A and G

Pyridimine

C and T

Purine structure

double ring

Pyridimine structure

Single ring

A and T bond

2 hydrogen bonds

C and G bond

3 hydrogen bonds

Chromatin

complex and DNA and protein

Homologous chromosomes

two copies of each chromosome

Gene

Portions of the DNA that encodes for proteins

Genome

All the DNA in a cell

Heterochromatin

highly condensed DNA

Euchromatin

less condensed DNA

Histone Protein

provide structural support for chromosomes

Interphase

Cells preform normal functions, less condensed, and duplicate

Prophase

Chromosome condense, nuclear membrane dissolves

Metaphase

Sister chromatids line-up

Anaphase

Sister chromatids pulled apart

Telophase

Nuclear membrane reforms

Replication machine

group of proteins that accomplish replication

Replication origin

where replication begins

Which protein binds to replication origin

initiator protein

Replication fork

moves in opposite direction to unzip the DNA strand

What drives the replication fork

helicase

Which direction is DNA synthesized in

5’-3’

DNA polymerase

adds nucleotides to 3’ end

Helicase

unwinds double helix by breaking hydrogen bonds

Primase

synthesizes RNA primers, needed for DNA polymerase to start

Single strand binding protein

binds to single DNA strands to keep them separated and hold them in place

Ligase

joins Okazaki fragments

Topoisomerase

relieves tension caused by unwinding of DNA

Gene expression

making a specific product useful to the cell

DNA coding strand

5’-3’

DNA template strand

3’-5’

RNA polymerase

transcribes RNA, adds nucleotides to 3’ end

mRNA

code for protein

rRNA

structure of ribosomes and catalyze protein synthesis

miRNA

regulate gene expression

tRNA

adaptors between mRNA and amino acid during protein synthesis

Promoter site

sits upstream, attaches RNA polymerase

Terminator

causes RNA polymerase and RNA transcript to be released

Sigma factor

recognizes promoter site

General transcription factors

required to initiate transcription by positioning RNA polymerase

5’ end of RNA processing

5’ cap

3’ end of RNA processing

poly A tail

Introns

noncoding segments of DNA that are removed

Exons

coding segments that stay

Genetic code

set of rules that translates nucleotides sequences of a gene to amino acid sequences of a protein

A-site

tRNA entry

P-site

forms peptide bond

E-site

tRNA ejected

Chaperone protein

help fold polypeptide chain to become functional protein

Proteolysis

protein degradation used to recycle amino acids