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molecular genetics Flashcards

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Biology 101 flashcards
1
Q

What did Gregor Mendell do?

A

traits are passed from parents to offspring

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2
Q

What did friedrich micsher do?

A

Discover “nuclein” (DNA) from looking at pus of wounded soldiers

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3
Q

Avery McCarty, McLoad

A

Nuclein is genetic material, not proteins as og thought

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4
Q

Erwin chargaf

A

Discovered nucleic bases and that A pairs with T and C pairs with G

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5
Q

Rosalind Franklin

A

Discovered theres 2 forms of DNA –> crystal structure
Figured out DNA is a helix first

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6
Q

James Walson and Francis Crick

A

Stole franklin’s work and published it

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7
Q

Double ringed nucleotides are:

A

purines, A and G

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8
Q

Single ringed nucleotides are:

A

Pyramidines, C and T

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9
Q

Structure of a nucleotide (DNA)

A

Built of deoxyribose sugar, nitrogenous base and phosphate group
- sugar has 5 C, 4 form the ring, the fifth sticks out
- base bonded to 1 prime, phosphate on 5 prime and hydroxyl on 3 prime (2 prime shows if its ribose or deoxy)
- 3 prime hydroxyl bonds nucleotides

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10
Q

Bases attaching

A
  • complimentry bases are attached by hyrdogen bonds
  • hydrogen bonds are strong so DNA is stable
  • A and T use 2 hydrogen bonds
  • G and C use 3 hydrogen bonds
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11
Q

The helix

A
  • Right handed, turns clockwise every 10 nucleotides
  • two strands run antiparallel one goes 5–> 3 other goes 3–> 5
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12
Q

What speeds up DNA replication

A
  • DNA replicates semi conserverative meaning they’re half old half new
  • Replication goes both way from the origin of replication
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13
Q

DNA replication initiation

A
  • DNA is opened at the replication origin by a group of enzymes, its called a replication bubble
  • DNA polymerase 3 enzymes insert in the space between strands. single stranded binding proteins stabilize single stranded DNA, prevent them from reforming their structure
  • Helicases unwind the helix just ahead of replication fork by breaking hydrogen bonds and DNA gyrase relieves the tension produced by the unwinding
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14
Q

DNA replication elongation

A
  • Needs an RNA primer to act as a starting point for adding nucleotides. the primer is made by primase
  • DNA Polymerase 3 can only add to 3 prime hydroxyl group of a chain of nucleotides, hydroxyl is needed for condensation
  • DNA replication can only happen 5 to 3
  • So lagging strand uses okazaki fragments, which requires one primer and polymerase PER fragment
  • RNA primers must be removed by DNA polymerase 1
  • Gaps filled between okazaki fragments are filled by DNA ligase
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15
Q

DNA replication termination

A
  • Daughter molecules re-wind
  • because new nucleotides can only be added to 3 prime end at the end of replication a gap is left at 5 prime end
  • eukaryotes have telomeres, highly repetitive DNA at the five prime end of a chromosome. Eventually they shrink, so telomerase adds telomeres back. Telomerase eventually fails, which is linked to aging.
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16
Q

DNA repair facts

A
  • 3 billion nucleotides per cell
  • DNA replication makes 1 mistake per 100 000 nucleotides
  • 120 000 every time a cell divides
  • proofreading fixes about 99% of those errors, leaving about 12 000 mistakes
17
Q

Proofreading & mismatch repair

A

Proofreading happens during DNA replication, mismatch repair happens after.
They have the same process: 1. polymerase 1 and 3 recognize structural imperfections in improperly paired nucleotides
2. the enzyme exonuclease backtracts past mispaired nucleotide and excises it
3. exonuclease replaces nucleotides with the proper nucleotide

18
Q

Initiation of DNA transcription

A
  • Each gene of double stranded DNA has a coding and template strand (coding will look the same as mRNA, tempate is used by taking the inverse to make mRNA)
  • start of a gene is indicated by a promotor sequence, where RNA polymerase can bind
  • promotor sequence can be found in the TATA box
19
Q

Elongation in DNA transcription

A
  • RNA polymerase opens DNA one section at a time
  • RNA polymerase works in the new strand, nucleotides added to 3 oh group
  • No okazaki fragments
  • Many RNA copies of the same gene can be made
20
Q

Termination of DNA transcription

A
  • RNA polymerase will continue along the DNA strand until a terminator sequence is encountered
  • After this, RNA polymerase molecule separates from the DNA strand and RNA molecule dissociates
  • becomes mRNA
21
Q

Processing of DNA transcription

A
  • only occurs in eukaryotes
  • initial mRNA is called pre-mRNA
    1. 5 prime cap made of a modified G nucleotide
    2. Poly-A tail attaches to 3 prime end made of modified A
    3. Splicing –> introns that dont code for anything are cut out by splicosome, exons that do code stay
22
Q

Initation in translation

A
  • mRNA reaches the cytoplasm
  • rRNA binds fivve prime end of mRNA at a special ssequence
  • Initiator tRNA with anticodon “UAC” binds ribosomal-mRNA complex (this anticodon matches start codon AUG
23
Q

Composition of a tRNA

A
  • three lobed shape
  • anti codon complimentry to mRNA’s codon at the bottom
  • amino acid at the top
  • when an amino acid is bound to tRNA its called amino-acyl tRNA (aatRNA)
24
Q

Elongation in translation

A

1.mRNA codon in A site forms a base pair with incoming aa-tRNA
2. peptide bond is formed joining new amino acid in A site to growing chain in P site
3. ribosome moves a distance of 3 nuclotidews along the rRNA molecule, called translocation (translocation brings the tRNA holding the chain into the P site, a new A site is exposed and the old tRNA from the P site moves to the E site

25
Q

Termination in translation

A
  • elongation continues until a stop codon is reached on the mRNA strand in the A site
  • previous tRNA, carrying the polypeptide chain remains in the P site until a protein called a release factor binds to the A site. The release factor cuts off completed polypeptide from tRNA
  • polupeptofe ois free to take its form
26
Q

Causes of mutations

A

Spontaneous mutations: results of errors in DNA replication, occur without chemical change or radiation

Induced mutations: Result of chemical (structure similar to nucleoties usually, interact chemically with DNA like nitrites or cigarette smoke) or physical agent (messes with DNA structure like UV or an XRay)

27
Q

SBLab squishing strawberries

A
  • step one, increases surface area to increase reactions
28
Q

SBLab salt solution

A
  • step 2, stabilizes DNA, Na in salt neutralizes negatively charged DNA and allows it to precipitate
29
Q

SBLab soap

A
  • step 3
  • pH precipitates lipids and proteins out of solution, breaks cell membranes
30
Q

SBLab filter

A
  • step 4
    removes big chunks (unseperated cells)
31
Q

SBLab add ethanol

A
  • fifth step
  • precipitated dna since its non soluable in ethanol
32
Q

Why did DNA curl around glass stirring rod

A
  • glass attracts neutral things
33
Q

Whats translocation mutation

A
  • swaps places with other part on dif chromosomes

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