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Bio 97: Midterm > DNA & RNA > Flashcards

DNA & RNA Flashcards

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1
Q

DNA and RNA are ____________.

A

Polynucleotides

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2
Q

What are the 3 parts of a nucleotide?

A
  • 5 carbon sugar (Pentose)
  • Nitrogenous base (ATCG)
  • One or more phosphate groups
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3
Q

What are pyrimidines?

A

C, T, U

  • has one 6 membered ring
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4
Q

What are Purines?

A

A, G

  • has a 6 membered ring fused to a 5 membered ring
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5
Q

What is the sugar for DNA?

What is the sugar for RNA?

What are their differences?

A

Deoxyribose

Ribose

Deoxyribose lacks an oxygen atom

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6
Q

In Animals, some DNA is found in the __________.

In Plants, some DNA is found in the __________.

A

Mitochondria

Chloroplasts

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7
Q

What are the 3 phases of Translation? Describe what happens in each one

A

Initiation
- initiator tRNA carrying the first amino acid binds to the mRNA start codon. The small and large units of the ribosome come together and translation begins.

Elongation
- Elongation Factor (EF) proteins recruit charged tRNAs to form more amino acids

Termination
- Release Factors (RF) bind to a stop codon in the A site and releases the polypeptides

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8
Q

A-T base pair has ___ hydrogen bonds

G-C bade pair has ___ hydrogen bonds

A

2

3

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9
Q

What is polycistronic mRNA?

A

mRNA that contains 2 or more genes

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10
Q

Why is the genetic code in triplets instead of doublets?

A

If the genetic code was in doublets, it would only produce 16(4^2) combinations of codons, which is not enough to specify 20 amino acids.

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11
Q

What are synonymous codons?

A

Codons that specify the same amino acid

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12
Q

Define Third-base Wobble

A

The flexibility of nucleotide pairing in the 3rd position of the codon and its anticodon

Eg,

UCC, UCU, UCA, UCG all code for Ser
- the 3rd base doesn’t matter

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13
Q

For translation, tRNAs need to be charged. What are they charged by? What does this do?

A

They are charged by Aminoacyl-tRNA Synthetases

  • these contact multiple points on tRNA to identify the proper tRNA to charge with an amino acid
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14
Q

What are the differences in transcription for prokaryotes and eukaryotes?

A
  • Eukaryotes have 3 RNA Polymerases, prokaryotes have 1
  • Eukaryotes form an initiation complex with transcription factors, prokaryotes don’t
  • RNA is transcribed first in the nucleus and second in the cytoplasm is eukaryotes, in prokaryotes they are done simultaneously
  • Eukaryotes have 5’ capping and polyadenylation, prokaryotes don’t
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15
Q

Define monocystronic

A

One gene in one mRNA

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16
Q

Define polycystronic

A

Many genes on one mRNA

17
Q

What is alternative pre-mRNA splicing?

A

When different mRNAs can be produced from the same gene, using different promoters or polyadenylation sites or by removal of different exons

18
Q

What are introns?

A

Segments of DNA that do NOT code for proteins and are spliced out

19
Q

What are exons?

A

Segments of DNA that DO code for proteins and are joined together after splicing

20
Q

What are alternative promoters?

A

Promoters that can initiate transcription at distinct start points in different cell types

21
Q

What is alternative polyadenylation?

A

When a gene has different polyadenylation signals (at the poly-A tail) to encode multiple mRNA transcripts

22
Q

What are the 4 components of PCR (Polymerase Chain Reaction)?

A
  • Double stranded DNA
  • 4 DNA Nucleotides
  • Heat stable DNA Polymerase
  • 2 different DNA primers
23
Q

How many cycles is PCR run through?

A

30-35

24
Q

Each PCR cycle _________ the number of copies of the target sequence

A

Doubles

25
Q

What DNA polymerase is used in PCR?

A

Taq polymerase (it is heat stable)

26
Q

What is autosomal inheritance?

A

Hereditary transmission of genes carried on autosomes

Autosomes are non sex chromosomes

27
Q

Dideoxynucleotides are used for ___________ because they are _________.

A

Sequencing, chain terminating

28
Q

What is true reversion?

A

Reverting the mutation at the same site or within the same codon

29
Q

What is intragenic reversion?

A

Reverting the mutation at a different part of the gene

30
Q

What is second-site reversion?

A

Reversion at a different site to generate original function

Suppressor mutations because they suppress mutated phenotype

31
Q

What is euchromatin?

A

Chromosome regions containing chromatid that is not densely compacted. The most expressed genes are located here

(These genes are more actively transcribed)

32
Q

What is heterochromatin?

A

Chromosome regions where chromatin is tightly condensed

Fewer expresses genes here

33
Q

Which DNA is more likely to hold repetitive DNA, euchromatic or heterochromatic?

A

Heterochromatic

34
Q

What is a nucleosome core particle?

A

A heterooctameric protein complex that contains two molecules each of the four histones H2A, H2B, H3 and H4.

35
Q

What are “beads on a string”?

A

Chromatin that consists of nucleosomes and linker DNA

36
Q

What’s the diameter of a nucleosome?

A

10 nm

37
Q

After chromatin has been condensed from a 10nm-fiber, what state is it next condensed into?

A

30nm-fiber (solenoid structure)

38
Q

Which RNA polymerase makes mRNAs in Eukaryotes?

A

RNA polymerase II

39
Q

Scaffold proteins condense chromatin into 300nm-fiber and it forms into _________ in metaphase.

A

Sister chromatids

Bio 97: Midterm (4 decks)

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