Biology - Molecular Biology of the Gene

DNA is a polymer. What is its monomer?

nucleotide

Nucleotides are made up of these three things:

pentose sugar, phosphate group, nitrogenous base

the pentose sugar in DNA is:

deoxyribose

the pentose sugar in RNA is:

ribose

what is the difference between deoxyribose and ribose?

deoxyribose lacks an oxygen atom on the second carbon

The numbering system used to identify the carbons in a nucleotide's sugar ring. The ___ carbon is attached to the phosphate group, while the ___ carbon is attached to the hydroxyl group.

5’, 3’

which nucleotide is this?

cytosine

which nucleotide is this?

thymine

which nucleotide is this?

uracil

which nucleotide is this?

adenine

which nucleotide is this?

guanine

which sugar is this?

deoxyribose

which sugar is this?

ribose

the daughter DNA strand only grows in the ___ → ___ direction

5’,3’

DNA replication begins at specific sites on the double helix called:

origins of replication

this enzyme is responsible for unwinding DNA to form replication forks:

helicase

what molecules hold apart DNA strands as they serve as templates of DNA synthesis?

molecules of single-strand binding proteins

this enzyme makes a short RNA strand called a primer:

primase

this enzyme joins nucleotides to form new DNA strands:

DNA polymerase

this strand is synthesized continuously towards the forking point:

leading strand

the lagging strand is made in sections called:

okazaki fragments

this enzyme joins the okazaki fragments to create the DNA strand:

DNA ligase

Replication proceeds in both directions creating what are called:

replication bubbles

When a double helix replicates, each of the two daughter molecules will have one _______ and one ______. This model is known as the _________.

old strand, newly-made strand, semi-conservative model

Only 1 out of every ____ nucleotides is incorrectly paired.

billion

these are protective sequences at the end of eukaryotic chromosomes:

telomeres

how do telomeres protect DNA?

telomeres protect the organism's genes from being eroded by DNA replication

human telomere sequence:

5′ TTAGGG 3′

why do telomeres shorten?

they shorten because DNA polymerase is unable to replicate the ends of DNA strands (where the telomeres are located).

the "end replication problem" was developed by:

James Watson and Alexei Olovnikov

it is believed telomeres are involved with this process:

the aging process

this enzyme adds telomeres sequences in eukaryotic gamete cells:

telomerase

what was discovered in Dolly the Sheep’s telomeres?

they were as long as a one-year-old sheep’s

the flow of genetic information:

DNA → RNA → proteins

what are the 3 kinds of RNA?

mRNA, tRNA, rRNA

what can triplets of the nitrogenous bases do?

specify the amino acids

a three base code in DNA or mRNA is called:

codons

which 3 codons are stop signals?

UAA, UAG, UGA

what codon is the start signal:

AUG

which researchers supported the one gene one enzyme hypothesis?

Beadle and Tatum

what does the one gene one enzyme hypothesis state:

the function of a gene is to dictate the production of a specific enzyme

what was the one gene one enzyme hypothesis transformed into:

the one gene one polypeptide hypothesis

the process of protein synthesis:

transcription and translation

transferring of genetic information from a DNA template to mRNA:

transcription

transcription occurs in the:

nucleus

this DNA strand provides a template for ordering the sequence of nucleotides:

template strand

three phases of transcription:

initiation, elongation, termination

a specific binding site for RNA polymerase and its helper proteins:

promoter

what does the promoter determine:

which strand in the double helix is used for transcription

this phase is transcription is the attachment of the transcription enzyme, RNA polymerase and the helper proteins (transcription factors), to the promoter:

initiation

this enzyme pulls the DNA strands apart and untwists a short portion of it. also it pairs RNA nucleotides to their DNA complements:

RNA polymerase

during this phase of transcription, RNA elongates.

elongation

during transcription, A pairs with:

U

a sequence of bases on the DNA that signals the end of a gene are called:

terminator

The entire stretch of DNA that is transcribed into an RNA molecule is called a:

transcription unit

after transcription, where does the mRNA go?

to a ribosome in the cytoplasm through the nuclear pores

this process occurs after transcription, and forms the full mRNA:

RNA processing

in RNA processing, what occurs?

a guanine cap and a poly-adenine tail are added to either side of the mRNA.

the guanine cap is added to which side?

the 5’ end

the adenine tail is added to which side?

the 3’ end

parts of the RNA that are not coded:

intron

coding regions of the RNA:

extron

in RNA splicing, what is removed?

the introns are removed

snRNPS stand for:

small nuclear ribonucleoproteins

snRNPs join with other proteins to form:

spliceosomes

this process enables a single gene to encode more than one kind of polypeptide:

alternative RNA splicing

tRNA molecule is made up of around:

80 nucleotides

a special base triplet in tRNA:

anti-codon

At the other end of the tRNA molecule is a:

site where an amino acid can attach

There are about __ different kinds of tRNAs

45

tRNA molecules match the appropriate ___ to the appropiate ______.

codon, amino acid

Ribosomes are where _____ actually takes place.

protein synthesis

ribosomes are made up of:

rRNA

The P site holds the tRNA with the _____. The A site holds the tRNA with the _____. Used tRNAs exit via the ___site.

growing polypeptide, next amino acid, E

label the ribosome:

A: P site, B: A site, C: E site, D: large subunit, E: mRNA binding site, F: small subunit

a cell reads an mRNA message and assembles a polypeptide in this process:

translation

in this phase of translation, it is established where the translation will begin:

initiation

during initiation, the initiator tRNA binds to the start codon with its anti codon:

UAC

the initiator tRNA always carries this amino acid:

methionine

during elongation of translation, what elongates?

the polypeptide at P site

what is the elongation process (3 steps):

codon recognition, peptide bond formation, translocation

in codon recognition, what happens?

the anticodon of a tRNA molecule pairs with the mRNA codon

in peptide bond formation, what happens?

the growing polypeptide attaches to the amino acid at the A site

in translocation, what happens?

the tRNA at the P site moves to the E site and exits. the tRNA with the polypeptide at the A site moves to the P site.

elongation continues until:

a stop codon reaches the ribosome’s A site

this protein binds to the stop codon and frees the polypeptide from the tRNA:

release factor

after the polypeptide is freed, what happens to the ribosome:

it splits into seperate sub-units

when a number of ribosomes trail along one mRNA chain, what is this called:

polyribosome

these mutations are caused by changes in a nucleotide base pair of a gene:

point mutations

what are the two types of point mutations?

base-pair substitutions, base-pair insertions or deletions

base-pair mutations may result in:

silent mutation, missense mutation, nonsense mutation, little effect on protein

when the change in the base pair alters the codon, but both codons translate into the same amino acid, this is called:

silent mutation

when the change in the base pair still makes an amino acid, just not the normal one:

missense mutation

when the change in the base pair translates into a stop codon:

nonsense mutations

when the new amino acid has properties similar to the original amino acid or its placement is not vital to the protein:

little effect on protein

whenever the number of nucleotides inserted or deleted is not a multiple of three:

frameshift mutation

about _ nucleotide in every 10^10 is altered:

1

these are physical and chemical agents that cause mutations:

mutagens

what are some physical mutagens:

x-rays, uv light

what is an example of a chemical mutation:

base analog