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nucleic acids Flashcards

1
Q

Describe the structure of nucleotides

A

pentose sugar
phosphate group
nitrogenous base
joined by phosphodiester bond

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2
Q

Nucleotides form the monomers of what?

A

Nucleic acids, DNA and RNA

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2
Q

Name the pentose sugar in DNA and RNA

A

deoxyribose and ribose

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3
Q

Name for a nucleotide with more than one phosphate group

A

phosphorylated nucleotides

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4
Q

What is a phosphorylated nucleotide?

A

A nucleotide with more than one phosphate group

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5
Q

Give an example of a phosphorylated nucleotide

A

ATP adenosine triphosphate (also adp and amp)

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6
Q

Nucleotides may be components of many _______

A

coenzymes

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7
Q

What does ADP stand for?

A

adenosine diphosphate

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8
Q

What does ATP stand for?

A

adenosine triphosphate

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9
Q

What is ATP?

A

energy rich end product of most energy-releasing biochemical processes, drives energy requiring metabolic processes

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10
Q

What are the functions of nucleotides?

A
  • monomers of nucleic acids
  • can become phosphorylated nucleotides
  • regulate many metabolic pathways
  • components of many enzymes
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11
Q

What is NADP?

A

coenzyme, contains adenine nucleotides, used in photosynthesis

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12
Q

What is NAD?

A

coenzyme containing adenine nucleotides, used in respiration

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13
Q

What is FAD?

A

coenzyme containing adenine nucleotides used in respiration

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14
Q

What is coenzyme A?

A

coenzyme containing adenine nucleotide, used in respiration

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15
Q

What is DNA?

A

genetic material used in development and functioning of all organisms;
macromolecule

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16
Q

Describe the structure of DNA

A

two polynucleotide strands run antiparallel,
forming double helix
strands held together by hydrogen bonds through complementary base pairing between nitrogen bases (adenine, guanine, thymine or cytosine)

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17
Q

What is a polymer made of nucleotides called

A

a polynucleotide

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18
Q

Which nucleotide bases are purines

A

Adenine and Guanine

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19
Q

Which nucleotide bases are pyrimidines?

A

Thymine and Cytosine

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20
Q

What are phosphodiester bonds?

A

covalent bond between pentose sugar and phosphate group in a nucleotide

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21
Q

How are the two DNA strands held together?

A

hydrogen bonds between nitrogenous bases

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22
Q

How many bonds connect adenine and thymine?

A

two

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23
Q

Which bonds connect nitrogenous bases in DNA

A

hydrogen

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24
How many bonds connect cytosine and guanine
three
25
What is the name for shape of DNA molecule?
double helix
26
Why is DNA double helix shaped?
for stability
27
What is the difference between purine and pyrimidines?
purines have two rings, pyrimidines have three rings
28
Describe meaning of 5' and 3' and how they describe the sugar phosphate backbone of DNA
5' where phosphate attached to 5th carbon of deoxyribose; 3' where phosphate attached to 3rd carbon; two polynucleotide strands run in opposite directions, 5 to 3 and 3 to 5
29
How is DNA organised in eukaryotic cells?
genome stored in the nucleus as chromosomes; small loop in self-replicating mitochondria and chloroplasts
30
Describe structure of chromosomes
DNA/chromatin wound around histone protein
31
How does DNA in mitochondria/chloroplasts differ to DNA in the nucleus?
nucleus DNA wound around histone proteins, other DNA is not
32
How is DNA organised in prokaryotic cells and viruses?
found as loop of 'naked' DNA in cytoplasm
33
How and when does DNA replication occur?
occurs when cells divide during interphase
34
What type of process is DNA replication?
semi-conservative
35
Outline process of DNA replication without naming enzymes
- double helix unwinds - hydrogen bonds between complimentary bases break - strands used as templates and complimentary base pairing - occurs between template strands and free nucleotides -adjacent nucleotides joined by phosphodiester bonds formed in condensation reactions
36
Outline process of DNA replication and state enzymes which catalyse each step
- DNA unzips using (DNA helicase) breaking hydrogen bonds between complimentary base pairs - strands are used as templates and complimentary base pairing between template strand and free nucleotides - adjacent nucleotides are joined by phosphodiester bonds using (DNA Polymerase) in 5 to 3 direction
37
How do DNA loops in prokaryotes/mitochondria/chloroplasts replicate?
semi-conservatively: bubble sprouts from loop, unwinds and unzips. complementary nucleotides join exposed bases, eventually whole loop copied
38
How are phosphodiester bonds formed during replication?
hydrolysis of free phosphorylated bases releases energy and phosphate groups used to form bonds
39
In what directions are free bases bonded to exposed DNA during replication?
5' to 3'
40
How are strands replicated in DNA replication?
leading strand continuously, lagging strand in fragments
41
Which enzymes catalyses the joining of fragments of replicated DNA?
ligase
42
Which enzyme catalyses unwinding of DNA?
gyrase
43
Which enzyme catalyses unzipping of DNA?
DNA helicase
44
Which enzyme catalyses the joining of free phosphorylated nucleotide bases to exposed DNA bases?
DNA polymerase
45
What is the product of DNA replication?
two DNA molecules, each made of one new strand and one old
46
Example of mutation which could occur during DNA replication
wrong nucleotide inserted, point mutation
47
How are mutations prevented during DNA replication?
enzymes proofread and edit out incorrect nucleotides
48
What are different versions of a gene called?
alleles
49
How are alleles formed?
by mutation
50
How does RNA differ from DNA?
- sugar ribose instead of deoxyribose - uracil replaces thymine - single-stranded - shorter - three forms: mRNA, tRNA, rRNA
51
State three forms of RNA
messenger, ribosomal and transfer
52
Four examples of specific protein shape
- enzyme complementary to substrate; - antibodies complementary to pathogen antigens; - receptors complementary to cell-signalling molecules; - channel proteins hydrophilic insides and lipophilic outside, fit specific molecules
53
Three main features of the genetic code
universal, degenerate, non-overlapping
54
What does universal mean?
same base triplets code for same amino acids in every organism
55
What does degenerate mean?
more than one codon can code for the same amino acid
56
What does non-overlapping mean?
bases read in threes, no crossover
57
Outline the process of transcription without stating enzymes
- hydrogen bonds between complimentary bases break - gene uncoil - temporary hydrogen bonding of RNA nucleotides and unpaired DNA bases on 'template' (antisense) strand - coding strand produced - copy that is complimentary to template strand - mRNA formed from adjacent nucleotides - joined by phosphodiester bonds - mRNA moved out of nucleus through a pore - attaches to ribosome - next translation
58
Outline the process of transcription stating enzymes
- hydrogen bonds between complimentary bases break - gene uncoils - (RNA polymerase) catalyses temporary hydrogen bonding of RNA nucleotides and unpaired DNA bases on 'template' (antisense) strand using (DNA helicase) coding strand produced - copy that is complimentary to template strand - mRNA formed from adjacent nucleotides - joined by phosphodiester bonds - mRNA moved out of nucleus through a pore - attaches to ribosome - next translation
59
Describe structure of ribosomes
two separate subunits made in nucleus, magnesium ions help bind them in cytoplasm, made protein and ribosomal RNA
60
Which ion helps ribosomal subunits bind?
magnesium ions
61
Describe the structure of a transfer RNA molecule (3)
single stranded, hairpin shape; one end trio nucleotides recognise and bind to amino acids; at loop another triplet (anticodon) attaches to codons on the RNA
62
What is a codon?
three nucleotide sequence codes for amino acid on mRNA
63
what is an anticodon?
on tRNA attaches to corresponding codon on mRNA during translation to create amino acid chain
64
outline the process of translation at a ribosome
- anticodon tRNA molecules bind by temporary hydrogen bonds - to complimentary codon on mRNA molecule - ribosome moves along mRNA - joins 2 amino acids by peptide bonds - ATP needed for polypeptide synthesis - polypeptide assembles mRNA breaks down - components recycled - new polypeptide is formed by chaperone proteins - help fold into tertiary structure
65
How do amino acids join to form a chain?
by polypeptide bonds during translation
66
Which proteins help fold amino acid chain?
chaperone proteins
67
What happens to mRNA after translation?
breaks down and can be recycled
68
How do anticodons bind to codons during translation?
by hydrogen bonds
69
Which enzyme catalyses the bonding of RNA bases to exposed DNA bases in transcription
RNA polymerase
70
Which enzymes catalyses the joining of fragments of replicated DNA?
ligase
71
Which enzyme catalyses unwinding of DNA?
gyrase
72
Which enzyme catalyses unzipping of DNA?
DNA helicase
73
Which enzyme catalyses the joining of free phosphorylated nucleotide bases to exposed DNA bases?
DNA polymerase
74
What is the product of DNA replication?
two DNA molecules, each made of one new strand and one old
75
Example of mutation which could occur during DNA replication
wrong nucleotide inserted, point mutation
76
How are mutations prevented during DNA replication?
enzymes proofread and edit out incorrect nucleotides
77
What are different versions of a gene called?
alleles
78
How are alleles formed?
by mutation

Biology (18 decks)

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