3) Nucleotides and Nucleic Acids Flashcards

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1
Q

What is the structure of a nucleotide

A

Pentose sugar
Nitrogenous base
phosphate group

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2
Q

Why are nucleotides important?
Give examples

A

They’re monomers that make up DNA and RNA .

ADP + ATP

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3
Q

What is DNA?
Describe DNA

A

Deoxyribose Nucleic Acid

Adenine, guanine,cytosine ,thymine

Contain 2 plynucleotide chains that run antiparralel.

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4
Q

What is a purine?
Give eg

A

Contain 2 carbon-nitrogen rings.

Adenine , guanine

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5
Q

What is a pyrimidine?
Give eg

A

Contain 1 carbon-nitrogen ring
Much smaller

Cytosine , thymine

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6
Q

What is Rna?
Describe it

A

Ribose Nucleic Acid

Adenine , cytosine ,guanine , uracil

Single chain polynucleotide

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7
Q

What is ADP and ATP

A

Phosphorylated nucleotides

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8
Q

How do you phosphorylate a nucleotide?

A

Add one or more phosphate groups to it.

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9
Q

Describe the structure of ADP and ATP

A

ADP - Adenine base , ribose sugar , 2 phosphate groups

ATP - Adenine base , ribose sugar , 3 phosphate groups

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10
Q

How does ATP provide enegy for chemical reactions

A

ATP is synthesised from ADP and inorganic phosphate group from energy-releasing reactions

ADP is phosophorylated to form ATP and a phosphate bond is formed.

Energy is stored in the bond, when ATP breaks fown , energy is released

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11
Q

How does a nucleotide join together to form polynucleotides

A

Join between phosphate groups by condensation reactions
Form phosphodiester bonds

Create sugar-phosphate backbone

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12
Q

How does 2 polynucleotide join to make an alpha-helix

A

Join by hydrogen bonding
By complementary base pairing

Adenine - Thymin

Guanine- Cytosine

Run antiparallel , hence double helix

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13
Q

How does DNA Self replicate
eg . semi-conservative replication

A

1) DNA helicase breaks hydrogen bonds , sttrands unzips

)2) Original strand acts as a template. Exposed bases join template by complementary base pairings.

3)Nucleotide join together by DNA Polymerase .Reform sugar-phosphate backbone . Hydrogen bonds between bases.
Strand twist into A-Helix

4) Each strand contains 1 strand from original DNA and new DNA strand

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14
Q

What is a gene

A

Sequence of DNA Nucleotides that code for a polypeptide.

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15
Q

How is DNA copied into RNA for protein synthesis

A

DNA found in nucleus.
DNA is too large to leave the nucleus.
Copied into mRNA by transcription
mRNA leaves nucleus and join with ribosomes to synthesis a protein by translation

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16
Q

What is mRNA

A

Made in nucleus
3 bases = codon
Carries genetic code , used to make protein from translation

17
Q

What is tRNA

A

Found in cytoplasm
Amino acid binding site at one and anticodon on other
Carries amino acid that are used to make proteins to ribosome during translatioin

18
Q

What is rRNA

A

Form subunites in ribosome
Moves alongthe mRNA strand during protein synthesis.
Helps catalyse formation of peptide bonds

19
Q

How is a genetic code Non-overlapping,degenerate and universal

A

Sequence of base triplets

Non-overlapping - Base triplets don’t share their bases.Each triplet is read in sequence

Degenerate - Some amino acids are coded for by more than one base triplets.

*Universal * - Same specific base triplets code for the same amino acids in all living things

20
Q

Describe Transcription

A

RNA Polymerase attatches to DNA helix

H Bonds break and strands unwind

One strand acts as a template to make an mRNA copy

RNA Polymerase lines up free RNA Nucleotides alongside template strand

Complementart copy of the strand ( T replaces with U )

RNA Nucleotides pair up bases and are joined together.

RNA Polymerase assemble mRNA Strands. H Bonds reform

Reach stop codon , Detatch from DNA.
mRNA moves out of nuclear pore

21
Q

Describe Translation

A

Amino acids join to make a polypeptide chain

mRNA attatches to ribosome.
Anticodon complementary to start codon attatch itself to mRNA .

“nd tRNA attatches itself to next codon on mRNA

rRNA catalyse formation of a peptide bond.Join amino acids together.

3rd tRNA brings next codon , previous tRNA moves away.

COntinues until reaches stop codon.
Polypeptide moves away from ribosome.