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Animal Health Science 1 > DNA > Flashcards

DNA Flashcards

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Biology 101 flashcards
1
Q

How many base pairs are there in a turn of DNA?

A

10.5

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2
Q

What are major and minor grooves?

A

Where the DNA wrap into a double helix each twist alternates in length due to one side of the base pair bond being longer than the other

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3
Q

How is DNA packaged?

A

DNA wraps twice around 4 histones

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4
Q

What are histones?

A

Positively charged molecules that condense DNA

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5
Q

How is bacterial DNA different to eukaryotic DNA?

A

Its circular

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6
Q

How is DNA replication initiated in bacteria?

A

Begins at 1 unique origin and proceeds bidirectionally, slow

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7
Q

How is DNA replication initiated in eukaryotes?

A

Begins at multiple origins and proceeds bidirectionally, much quicker

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8
Q

What is DNA polymerase?

A

An enzyme that replicates DNA with a primer

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9
Q

What unwinds the double helix of DNA?

A

Helicase

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10
Q

What makes the primers?

A

Primase

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11
Q

What direction does DNA replication occur in?

A

5’ to 3’

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12
Q

What is telomerase?

A

An enzyme that has a bit of DNA with RNA on it that can start making DNA without a primer

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13
Q

What is telomerases function?

A

To allow space for a primer to be added without important DNA being lost
Its activity decreases over time which is why we get old

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14
Q

What are the 4 types of DNA repair?

A

Mismatch repair
Direct repair
Excision
Nonhomologous end joining

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15
Q

What are the 3 stages of gene expression?

A

DNA replication
Translation
Transcription

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16
Q

In eukaryotes what does DNA polymerase 1 synthesise?

A

rRNA

17
Q

In eukaryotes what does DNA polymerase 2 synthesise?

A

mRNA

18
Q

In eukaryotes what does DNA polymerase 3 synthesise?

A

tRNA

19
Q

How is mRNA processed after being transcribed?

A

Spliced to remove the introns

Capped and polyadenylation

20
Q

What is capping and polyadenylation?

A

Where a 5’ cap is added so the ribosome cane recognise the start of the gene

21
Q

What is alternative splicing of mRNA?

A

When some adjacent exons are removed to produce multiple proteins from one gene

22
Q

What is a transcription factor?

A

Regulates transcription

Either activator or repressor of RNA polymerase

23
Q

What are histone tails?

A

Chains of amino acids that are positively charged so attract the DNA to wrap around them

24
Q

How can histones be modified to bring about post translational modification@

A

Histone acetylation

Histone deacetylation

25
Q

What is histone acetylation?

A

transcriptional activation - When acetyl groups are added to the histone tails which neutralises the tails so DNA doesn’t wrap around as well

26
Q

What is histone deacetylation?

A

Transcriptional repression - When acetyl groups are removed from histone tails so its more positive and DNA wraps around more

27
Q

What is epigenetic gene regulation?

A

When modifications change gene expression without changing the DNA sequence

28
Q

What forms of epigenetic gene regulation are there?

A

DNA methylation - silences genes
Histone modification
miRNA related gene silencing

29
Q

What are aminoacyl-tRNA synthetases?

A

Enzymes that join tRNA and amino acids together

30
Q

What are the 3 active sites of ribosomes?

A

A site - aminoacyl-tRNA
P site - peptidyltransferase
E site - exit

31
Q

What is a polyribosome?

A

One piece of mRNA with lots of ribosomes attached to it all translating at once

32
Q

What are the 3 main checkpoints in the cell cycle?

A

G1 - before S phase
G2 - after S phase
Mitosis - before cytokinesis

33
Q

What are cyclins?

A

Proteins that control the cell cycle

34
Q

How do cyclins control the cell cycle

A

They have different levels through the cell cycle

Protein kinase is activated by them which allows the cell cycle to occur

35
Q

What is an example of cyclins?

A

Retinoblastoma (Rb) protein

36
Q

How does Rb protein control the cell cycle?

A

Binds to the transcription factor that controls the S phase so cycle stops

Animal Health Science 1 (33 decks)

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