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4 - Genetic information Flashcards

1
Q

The fixed position occupied by a gene on a DNA molecule

A

Locus

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2
Q

How is a gene code for a polypeptide?

A

Nucleotide sequence in triplets which codes for the primary structure of the polypeptide chain

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3
Q

Exon

A

Triplet sequence coding for a polypeptide

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4
Q

How is a phosphodiester bond formed between 2 nucleotides in DNA?

A

Condensation reaction between deoxyribose + phosphate, catalysed by DNA polymerase

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5
Q

Where is a non-coding base sequence positioned?

A

Between genes

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6
Q

3 Ways in which the structure of the chromosome may differ along its length, resulting in more stain binding in some areas

A

Differences in base sequences

Differences in histone

Differences in supercoiling

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7
Q

Homologous chromosomes

A

2 chromosomes which carry the same genes

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8
Q

Intron

A

Non-coding region of DNA

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9
Q

What does tRNA have that mRNA does not?

A

Hydrogen bonds
Amino acid binding site
Anticodon

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10
Q

What does mRNA have that tRNA does not?

A

Codon

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11
Q

What is the difference in shape of mRNA and tRNA?

A

mRNA - linear

tRNA - clover leaf shaped

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12
Q

What is the difference in structure between mRNA and pre-mRNA? Why?

A

mRNA has fewer nucleotides because of splicing

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13
Q

How is one amino acid added to a polypeptide chain during translation?

A

tRNA brings specific amino acid
(tRNA) anticodon binds to (mRNA) codon
Amino acids joined via condensation reaction

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14
Q

How is mRNA produced from an exposed template strand of DNA?

A

Free RNA nucleotides form complementary base pairs

Phosphodiester bonds form
by action of RNA polymerase

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15
Q

How is mRNA formed by transcription in eukaryotes?

A

Hydrogen bonds break between bases

1 DNA strand acts as a template

Free nucleotides align by complementary base pairing
Uracil instead of thymine in RNA

RNA polymerase joins nucleotides, forming phosphodiester bonds

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16
Q

Splicing

A

removing introns from pre-mRNA to form mRNA

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17
Q

How is a polypeptide formed by translation of mRNA?

A

mRNA attaches to ribosomes
Anticodons bind to complementary codons
tRNA brings specific amino acid
Peptide bonds formed using ATP
tRNA released
Ribosomes moves along mRNA to form polypeptide

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18
Q

Proteome

A

The full range of proteins a cell can code for

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19
Q

Transcription

A

conversion of DNA –> RNA

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20
Q

Translation

A

The converssion of RNA –> proteins

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21
Q

What enzyme breaks the hydrogen bonds between the 2 strands?

A

RNA polymerase

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22
Q

Outline Transcription

A

mRNA associates with ribosome which frinds the start codon

tRNA brings specific amino acid

Ribosome fits 2 codons (codon-anticodon)

amino acids joined by peptide bonds

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23
Q

Types of mutation

A

Substitution
Deletion
Polyploidy
Non-disjunction

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24
Q

Substitution

A

When one nucleotide in the base sequence is replaced by another one

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25
Deletion
A single nucleotide is lost, causing a frameshift
26
Addition
A nucleotide is added, causing a frameshift
27
Polyploidy
An individul has 3 or more sets of chromosomes
28
Non-disjunction
Chromosomes fail to seperate properly in Meisosis
29
Independent Assortment
Meiosis I - homologous chromosomes line up in random pairs
30
Crossing Over
When pairs of chromosomes line up, they can exchange some of their genetic material
31
Meiosis I
Homologous chromosomes line up Crossing over at the chiasmata
32
Meiosis II
Chromatids seperate, producing 4 haploid daughter cells
33
Mutagenic agent
A factor that increases the rate of mutations
34
Causes of genetic diversity
Independent segregation Crossing over
35
Why might a mutation have no effect on the individual
Genetic code is degenerate Mutation on Intron No effect on tertiary structure New allele is recessive
36
How might a mutation have a positive effect
Changes to properties of protein lead to greater reproductive success or greater chances of survival
37
Where is prokaryotic DNA located
In the cytoplasm as they have no nucleus
38
Coiling of prokaryotic DNA
Supercooling - condenses circular chromosomes so that they can fit inside the cell
39
Length of prokaryotic DNA
Chromosomes are short
40
Eukaryotic DNA
Histone-bound In Nucleus Homologous pairs Long and linear
41
How are the presence of DNA in mitochondria and chloroplasts explained?
Endosymbiotic theory
42
Endosymbiotic theory
States that bacterial cells were engulfed by a larger cell during evolution
43
Process of endosymbiotic theory
The bacteria and host cell formed a beneficial symbiotic relationship The bacterial cells became incorporated into the larger cell to become organelles
44
What were the bacterial cells incorporated into host cells thought to become?
Mitochondria and chloroplasts
45
Why is is thought that mitochondria and chloroplasts were once free-living bacteria?
When they were free-living bacteria, they needed their own DNA to survive This explains why there is still some DNA in mitochondria and chloroplasts
46
Role of mitochondrial DNA
Encodes enzymes used in respiration
47
Role of chloroplast DNA
Encodes enzymes used in photosynthesis
48
What encodes a specific amino acid?
Codon
49
Role of mRNA
The base sequence in a gene is made into a polypeptide by copying DNA into mRNA mRNA is then copied into the corresponding polypeptide
50
Functional RNA
Some genes encode a function RNA molecule instead of a polypeptide Functional RNA are necessary for protein synthesis
51
Transfer RNA
Helps find the correct amino acids for a specific codon
52
Ribosomal RNA
Part of a ribosome, centre of protein synthesis
53
Codon
3 bases that encode a specific amino acid
54
What happens when a gene is translated for protein synthesis?
The introns are removed from the sequence
55
Features of the genetic code
Universal Non-overlapping Degenerate
56
Genetic code as degenerate
Some amino acids are encoded by more than one codon This is because there are 64 possible triplet codons and only 20 amino acids
57
Genetic code as non-overlapping
No overlap between triplet codes
58
Genetic code as universal
The same 4 bases are used in the DNA of every organism The same codons encode the same amino acid in every organism Codons in DNA are transcribed into mRNA and translated into amino acids in every organism
59
Genome
Complete set of genes in an individuals DNA
60
Proteome
Full range of proteins an individual can produce
61
2 processes involved in synthesizing protein from a base sequence
Transcription Translation
62
How is mRNA produced?
Transcribed from DNA in the nucleus to produce single stranded RNA mRNA strand in complementary to the DNA base sequence
63
Where does mRNA travel?
From the nucleus to the ribosomes in the cytoplasm
64
Role of ribosomes in synthesising polypeptide
Translate mRNA into amino acids and synthesised the polypeptide
65
tRNA - Shape and role
Forms a clover-like shape and is vital for translation tRNA reads the mRNA codons and brings the corresponding amino acid into the tibosomes
66
Why is it important that the correct amino acid is brought to the ribosomes by tRNA?
So that the protein is assembled correctly
67
tRNA anticodon
Complementary to a specific mRNA codon The amino acid that corresponds to a specific anticodon binds to a specific attachment site on the tRNA molecule
68
RNA polymerase
Enzyme which allows transcription to take place Binds to the locus of the gene to be transcribed
69
What happens when RNA polymerase binds to DNA?
The hydrogen bonds between adjacent nucleotides break DNA strands separate Bases of target gene are exposed
70
How are free-floating nucleotides binded to the template strand in transcription?
RNA polymerase
71
What do RNA nucleotides form when binding to template strand?
A strand of mRNA complementary to template strand
72
What forms between adjacent nucleotides?
Phosphodiesterase bonds in a condensation reaction
73
Role of STOP codon
Signals to RNA polymerase to stop separating DNA and producing mRNA
74
What happens when the mRNA strand is separated from the template strand?
The hydrogen bonds between the 2 strands of DNA form again and the strands join together
75
What is mRNA used in?
Translation
76
Where does translation take place?
Cytoplasm
77
How many bases can fit inside a ribosome at any one time?
6 bases (2 codons)
78
How is tRNA binded in translation?
One molecule of tRNA binds to the first codon in the ribosome tRNA has an anticodon complementary to a specific codon Anticodon allows correct tRNA molecule to bind to correct codon
79
How is an amino acid bound to tRNA?
ATP
80
When is the polypeptide chain released from the ribosome?
When the ribosome reaches a STOP codon
81
Pre-mRNA
mRNA before it has been spliced
82
When is pre-mRNA spliced?
Before it enters the ribosome for translation
83
Splicing
Removes introns from the mRNA
84
Role of RNA polymerase in prokaryotes
Catalyses every step of transcription including the separation of DNA strands and the production of the mRNA strand
85
What do ribosomes translate mRNA into?
Amino acids
86
Non-Dysjunction
Where chromosomes do not separate properly
87
2 ways of increasing genetic variation in meiosis
Crossing over Independent segregation
88
Crossing over
Chromosomes line up at centre of cell in homologous pairs and sections of DNA are swapped between chromosomes
89
Independent segregation
The chromosomes in a homologous pairs are randomly separated in meiosis I to produce 2 genetically different daughter cells
90
Random fertilisation
Gametes randomly fuse together during sexual reproduction to produce a diploid cell
91
How is genetic diversity in a population increased?
Mutations - creation of new alleles Gene flow - introduction of new alleles by migration
92
Stabalising selection
The process where natural selection favours an average phenotype
93
Directional Selection
The process where natural selection favours an average phenotype
94
Types of adaptation
Behavioural Physiological Anatomical
95
Species
Organisms that can interbreed to produce fertile offspring
96
How are potential mates of the same species identified?
Courtship behaviour
97
Courtship behaviours
Complex displays which help an individual to attract a mate
98
Phylogeny
Evolutionary relationships between organisms
99
Taxa
A group of closely related organisms
100
Stages of the hierarchy
Domain Kingdom Phylum Class Orer Family Genus Species
101
Binomial naming system
Consists of the genus and the species of an organism
102
Identifying evolutionary relationships through antibody-antigen interactionsss
An organisms antibodies can be isolated with another organisms proteins to see how many antigen-antibody complexes are formed
103
Investigating evolutionary relationships through genome sequencing
The more similar the base sequences between organisms, the more closely related they are
104
Ways of determining evolutionary relationships
Antibody-antigen complexes Base sequencing Amino acid sequencing
105
Species richness
The number of species in a habitat or community
106
How do pesticides reduce biodiversity?
Direct removal of pests The species that feed on pests cannot survive
107
How do herbicides reduce biodiversity?
Direct removal of plants Species that feed on the unwanted plants cannot survive
108
How does deforestation reduce biodiversity?
Direct removal of species (trees) Removal of habitats causing species to die
109
Environmental Stewardship Scheme
Encourages farmers to balance agriculture with conserving biodiversity

Biology (7 decks)

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