Nucleic Acids Flashcards

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1
Q

Structure of Nucleotide

A

Nitrogenous/Organic base
Deoxyribose sugar (pentose sugar)
Phosphate group

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2
Q

Bonds in DNA - Phosphodiester bond

A

Forms between the deoxyribose sugar on one nucleotide and the phosphate group on other

Forming a dinucleotide

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3
Q

Bonds in DNA - hydrogen

A

Weak bonds between the bases

join two strands together

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4
Q

Bonds in DNA - hydrogen

A

Weak bonds between the bases

join two strands together

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5
Q

How is DNA adapted to be a storage molecule?

A

Sugar phosphate backbone - provides strength and stability

Large molecule so can store lots of information

Coiled into a helix so compact

Double stranded so replication can occur semi conservatively

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6
Q

mRNA

A

Copy of a gene from DNA

Much shorter than DNA so can leave the nucleus

Short-lived - only needed temporary to create a protein

Single stranded - every 3 bases code for a specific amino acid. these 3 bases are codons

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7
Q

tRNA

A

Only found in the cytoplasm

Single stranded but folded into a clover leaf shape which is held in place by hydrogen bonds - approximately 75 nucleotides long

Attaches to one of the amino acids and then transfers this to the ribosome to create the polypeptide

A reigon of 3 bases is an anticodon

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8
Q

Chargaffs rule

A

A purine always pairs with a pyramidine

Purines:
Adenine
Guanine

Pyramidines:
Thymine
Cytosoine

There will be equal amounts of adenine and thymine
and equal amounts of cytosine and guanine

If we know one we can work out the other.

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9
Q

Bonds in ATP

A

The bonds between the end 2 phosphates are unstable and have a lower activation energy. This means they are easy to break. ATP/energy is released once broken.

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10
Q

Hydrolysis of ATP

A

ATP —> ADP + Pi

H20 required

Energy released

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11
Q

Condensation of ATP

A

ATP <——– ADP + Pi

H2O relrased

energy used up

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12
Q

What happens to the phosphate that is released when ATP is hydrolysed

A

The phosphate group is often transferred to other molecules to lower their activation energy and make them more reactive (phosphorylation)

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13
Q

What is a Gene?

A

A gene is a section of DNA that codes for a particular protein/polypeptide and codes for functional RNA

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14
Q

Genes in DNA

A

DNA molecules have many genes along their length and have a specific position called the locus.

Between the genes are non coding repeats. The number of repeats vary from person to person so can be used in genetic fingerprinting.

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15
Q

Give two ways in which the hydrolysis of ATP is used in cells

A

Metabolic reactions such as respiration

To add phosphate to other substances and make them more reactive

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16
Q

Describe how ATP is resynthesised in cells

A

From ADP and phosphate

By ATP synthase

17
Q

DNA is a polymer of nucleotides. Each nucleotide contains an organic base.

Explain how the organic bases help to stabilise the structure of DNA

A

Hydrogen bonds between the base pairs hold two strands together

Many hydrogen bonds provide strength

18
Q

Give three ways in which the DNA in a chloroplast is different from DNA in the nucleus

A

DNA in a chloroplast is shorter

DNA in a chloroplast is circular

DNA in a chloroplast has fewer genes

19
Q

Explain how a change in a sequence of DNA bases could result in a non functional enzyme

A

Change in amino acids
Change in hydrogen bonds ——> change in tertiary structure
Enzyme-substrate complexes form

20
Q

Structural differences between a DNA molecule and an mRNA molecule

A

DNA has thymine whereas mRNA has uracil

DNA has deoxyribose sugar, mRNA has a ribose sugar

DNA is larger whereas mRNA is shorter

DNA is double stranded whereas mRNA is single stranded

21
Q

Structural differences between DNA and tRNA

A

DNA has thymine whereas tRNA has uracil

DNA is linear whereas tRNA is clover-leaf shaped

DNA has a deoxyribose sugar, tRNA has ribose

22
Q

Give one difference between the function of DNA and RNA

A

DNA - holds genetic information

RNA - Transfers genetic information from DNA to ribosomes

23
Q

What are ribosomes formed from?

A

RNA and proteins

24
Q

Why did scientists initally doubt that DNA carried the genetic code?

A

Due to the relative simplicity

25
Q

What is a locus?

A

The location of a gene on a particular DNA molecule