genetics exam 3 (SI notes) Flashcards

She used X-Ray diffraction to see crystal structure of DNA

They figured out the Double Helix Structure of DNA

found that A and T pair and G and C pair

That DNA replicates Semiconservatively. They also found out that it was NOT conservative or dispersive

that there is a “Transforming Factor” responsible for heredity

That DNA was the transforming factor in hereditary material

Recreated Griffith experiments but destroyed (1 at a time) proteins, lipids, RNA, and DNA

That DNA is hereditary material and is found in viruses too

They tagged the Sulfur of a bacteriophage (proteins) and the phosphorus (DNA). Thus phage infected a cell, and all new viruses created had that P tag. NOT the S one.Proving finally that DNA was the genetic material

only one strand of new DNA comes directly from parent molecule

He labeled both strands of DNA and let it replicate. Through this they discovered that there was one strand of parent DNA in each new molecule

By replicating the 2 molecules again and again found there were just the two original strands, and 6 new strands

There was a Transforming Principle responsible for heredity

SIII virus kills mice, RII lets mice live, SIII heat killed lets mice live.

This means that some transforming principle passed from the shocked SIII to the RII

Because DNA is super stable so is hard to get rid of, so in
bacteria if it can jump to a cell with working organelles, it will, and then will become a part of that cell

It runs in 2 antiparallel strands. (5'-3')

By hydrogen bonds between A-T and G-C

2

3

phosphodiester bonds

The B form naturally in living organisms

the turns in the DNA double helix which forms major and minor grooves

Bidirectional and proceeds from multiple replication origins

bidirectional but has ONE replication origin

Unique in prokaryotes and eukaryotes, conserved across species, and essentially tell DNA polymerase where to bind and start replication

It breaks DNA hydrogen bonds and unwinds DNA

SSBs

Extends DNA strands to replicate DNA

RNA Primer made by primase

main replication enzyme

continuously and it makes the leading strand

Okazaki fragments

ligase

its 5-3 exonuclease activity to remove the primer and then its 5-3 polymerase activity to elongate the gaps in the strand

topisomerase

caps at the end of linear chromosomes. They help to combat the shortening of chromosomes in each replication
cycle

They are formed by T loops and protected by the protein sheltrin

adenine, uracil, cytosine, and guanine (no T)

single stranded (so it is way less stable)

It includes an extra OH on the 2’ carbon

made by protein coding genes and is intermediate between
DNA and proteins

NOT from protein coding genes...works with proteins to form ribosomes

NOT from protein coding genes...binds to amino acid to add it into growing protein chain

provides template for synthesizing telomeres

In mRNA processing and splicing out introns

pairs with mRNA to alter stability

double stranded RNA to also alter mRNA stability

the strand of DNA that RNA polymerase binds to and assembles a complementary strand of nucleotides to

coding strand. It is where the actual genes being transcribed

true

The promoter region

sequences to help stop transcription (close to 3’ end)

The sigma subunit actually identifies the promotor region and allows RNA Polymerase to bind. The RNA Polymerase holoenzyme complex then unwinds the DNA to form an open promotor complex. After 8-10 nucleotides have been transcribed, the sigma subunit then
dissociates from the complex

the DNA continues to unwind in front of RNA Polymerase and reforms the double helix behind it

1. Intrinsic Termination happens in most prokaryotes

2. Rho-Dependent Termination needs the protein rho

The termination sequence is a bunch of inverted repeats, followed by a tail of Adenines.

ex: GGGGGGCCCCAAAAAAAAA

Rho moves up the mRNA, forces it to form a loop, detaching it from the DNA and kicking RNA Polymerase off

rRNA

mRNA, miRNA, siRNA and snRNA

tRNA, miRNA, siRNA one snRNA, and one rRNA

proteins around the promotor to enhance the level of
transcription...i.e. gene expression

DNA so it can’t be transcribed as easily...decreases gene expression

1. Capping 5’ mRNA (Guanylyl transferase adds a special Guanine nucleotide to the 5’ end of the mRNA to
serve as a cap)

2. 3’ Poly-A tail (A polyadenylation sequence is at the 3’ end of the mRNA . The mRNA is cleaved after this sequence and then PAP and CPSF then add up to 200 As.)

This protects the mRNA molecule from rapid degradation and helps with later translation

This protects mRNA from degradation and helps with translation

Eukaryotic mRNA is unique in that intronic (non-coding) regions and spliced (cut) out of final transcript. This is important in correct protein formation

In splicing, you have a 5’ splice site, 3’ splice site, and a branch
point. Introns are removed by an snRNA - protein complex called a spliceosome. The 5’ end is cut first, then 3’ end. They are then ligated together to form a lariat intron structure

1. Alternative Intron Splicing

2. Alternative Processing

3. Alternative Polyadenylation

4. RNA Editing and processing

20 with unique chemical properties

They are distinct and give these amino acids their unique
properties

a peptide bond between amino acids which forms a growing polypepetide chain

A group of 3 nucleotides on an mRNA strand and they code for one amino acid

start codon: 5’ AUG (always)

end codon: UGA, UAG, UAA 3’

methionine (met)

small Untranslated regions (UTRs) on the 5’ and 3’

a combination of rRNA and proteins found in ALL living organisms

They bind mRNA, facilitate pairing of correct tRNAs carrying amino acids to catalyze the formation of peptide bonds to
create proteins

3 (A, P, E)

where tRNAs carrying amino acids first bind to the ribosome (NOT THE FIRST ONE THOUGH)

where the ribosome transfers amino acids into the polypeptide chain

where the tRNA will leave the ribosome after dropping off its amino acid

40s and 60s to create 80s

30s and 50s to create 70s

GTP

proteins that facilitate mRNA and ribosome binding

They use GTP hydrolysis to help create growing protein chains

tRNA molecules WITH an amino acid attached to them

They bind to the codon in the A site after the stop codon has been reached (basically end translation)

a Shine-Dalgarno sequence found in all prokaryotic mRNAs

N-formylmethionine (fMET) instead of normal methionine

the p site (all other tRNAs will first bind to the A site)

the Kozak Sequence. (everything else is similar to prokaryotes)

aminoacyl-tRNA synthetase binds the correct amino acid to the tRNA with the correct anticodon (this uses ATP)

The correct tRNA will have a complementary sequence to the correct codon in its anticodon stem. Once one of the three stop codons binds in the A site, a Release Factor (RF) will bind in the A site as well

64 including the 3 stop codons

more than one codon can code for an amino acid ( but there are 3 exceptions - methionine and tryptophan)

methionine and tryptophan (helpful in protecting against mutations)

the third nucleotide in a codon is least important, and has the
flexibility to mutate and still bind the original amino acid

true

signal sequences to lead the new protein chain to other organelles for processing or packaging

by showing that a single nucleotide substitution only affected one amino acid

by looking at the reading frame and it can cause frameshift mutations

Mutations that occur in somatic, body cells and they can NOT be passed down

mutations that occur in egg/sperm cells and these CAN be passed on

only one specific place in the DNA (ex: one base pair was deleted)

when you swap one nucleotide for another

a purine switches with a purine (or pyrimidine for pyrimidine)

a purine and pyrimidine switch places

when you insert or delete nucleotides NOT in a multiple of 3 (they change the reading frame of the DNA sequence and can leave it nonfunctional)

silent, missense, and nonsense

A nucleotide is substituted, but the amino acid does NOT change (Ex: UUU and UUC both code for Phe)

A nucleotide is substituted, and the amino acid DOES change
(Ex: UUU codes for Phe but UUA codes for Leu)

A nucleotide is substituted and creates a premature stop codon (Ex: UAU codes for Tyr and UAG is a stop codon)

alter the expression of the protein product but have no affect on the protein coding DNA sequence

any types of mutations that occur in the consensus sequences in the promotor region. They mainly affect RNA polymerase

the amount of protein produced

They occur in the specific splice sites of introns and they can actually change the protein produced

new splice sites in mRNA, additionally changing the
protein produced (they can accidentally skip some exons)

Going from wild type to mutant allele

a codon receives a second mutation that restores the original amino acid

reversions occurring somewhere else in the gene

(a frameshift fixing another frameshift mutation)

in a DIFFERENT gene that compensates for the original mutation

true

breaks the nucleotide from the backbone, if unprepared is replaced by an A

occurs when an amino group is lost from a nucleotide