Nuclei acids Flashcards

1
Q

What is dna made up of

A

2 polynucleotide chains which twist to form a double helix

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1
Q

Describe a dna nucleotide

A
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2
Q

How are the components of dna joined

A

As a result of a condensation reaction

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3
Q

How are nucleotides joined together

A

Through condensation reaction between deoxyribose of 1 mono nucleotide and phosphate group of next by a phosphodiester bond

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4
Q

What are the base pairs on DNA?

A

Adenine pairs with thymine
Guanine pairs with cytosine

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5
Q

What is key information from the mark scheme about DNA and RNA

A

DNA and RNA are polymers of nucleotides

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6
Q

What do histones do

A

Organise and condense DNA tightly so it fits into nucleus

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7
Q

What does DNA stand for

A

Deoxyribonucleic acid

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8
Q

What does RNA stand for

A

Ribonucleic acid

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9
Q

What are the bases in RNA?

A

Adenine to uracil
Cytosine to guanine

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10
Q

Is RNA single or double stranded

A

Single

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11
Q

Is it a short or long, polynucleotide chain

A

Relatively short

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12
Q

Who worked out structure of DNA

A

Watson and Crick

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13
Q

What is phosphodiester made of

A

2 ester bonds and a phosphate group

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14
Q

How is DNA adapted to carry out its function

A

Large molecule- carries lots of genetic material

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15
Q

Why have many scientists doubted dna carried genetic code

A

Because of its simplicity

16
Q

How is dna adapted to carry out function (2 strands..)

A

2 strands joined by hydrogen bonds allow to separate during dna replication

17
Q

How is DNA adapted to carry out its functions( base pairing)

A

Base pairing- dna can replicate and transfer information mRNA

18
Q

How id DNA adapted to carry out it’s function(generations)

A

Can pass genetic information from generation to generation without signifant change. Mutations are repaired

19
Q

How do you package DNA

A

DNA wrapped around histones, which are protein beads to form a structure called a nucleosome. Chain of nucleosome is called chromatin. chromatin is woundup to form a single chromosome.

20
Q

What is the function of R.N. A

A

to transfer genetic code found in DNA to ribosomes

21
Q

What is each DNA polynucleotide strands said to have

A

A 3’ end and a 5’ end

22
Q

What does three end and a five end do

A

They run in opposite directions they are antiparallel

23
Q

Are ribosomes bigger in eukaryotic cells or prokaryotic cells

A

Eukaryotic (80S)

24
Q

Are ribosomes surrounded by membranes

A

No

25
Q

What is the purpose of semiconservative replication?

A

Before cell divides, it needs to copy DNA within so that to new daughter cells will both receive for copies of parental DNA

26
Q

Why is it called semiconservative replication?

A

In each new DNA molecule one DNA strand is from original DNA molecule and one is new

27
Q

Why is it important to retain one original DNA strand?

A

It insures genetic continuity between generations of cells

28
Q

What does semiconservative replication need?

A

Free Nucleotides
Both strands of DNA to act as a template, enzyme DNA polymerase, DNA helicase and a source of chemical energy

29
Q

Describe semiconservative replication

A

Enzyme DNA Heli case breaks hydrogen bonds between complimentary base pairs
Double helix, then unwinds
Each exposed polynucleotide strands then acts as a template to which complimentary three nucleotides bind by specific base pairing
Nucleotides joined in a condensation reaction by enzyme DNA polymerise to adjacent ones

30
Q

What were the three possible ways, scientist, believed DNA could replicate

A

Fragmented, semi, conservative or conservative

31
Q

Who was Watson and Criks theory proved by

A

Meselson and Stahl

32
Q

How did Meselson and Stahl prove it was semi conservative replication

A

Heavy 15 and culture bacteria was spun in centrifuge. DNA containing heavy nitrogen settled in a bottom of tube. This was added to only lighter 14 and nitrogen it was left long enough for one round of DNA replication, then centrifuged

33
Q

What would Meselson and Stahl findings have been if it was conservative replication

A

The original DNA, which was the only heavy nitrogen what is settle at the bottom and the new DNA, which was only lighter nitrogen would be at the top

34
Q

What did the test tube show to prove it was semiconservative replication

A

DNA containing mixture of light and heavy nitrogen settled in middle of test tube