Topic 4 Genetic Information, Variation and Relationships Flashcards
(123 cards)
1
Q
Allele definition
A
An alternate form of a gene
2
Q
Gene definition
A
A section of DNA which codes for a protein
3
Q
What is DNA?
A
Deoxyribonucleic acid
The molecule in cells that stores genetic information
4
Q
What is a chromosome?
A
A threadlike structure made up of one long DNA molecule
5
Q
What is genetic diversity?
A
The total number of different alleles in a population
6
Q
Population definition
A
A group of organisms of the same species that live in the same place and can interbreed
7
Q
Species definition
A
All of a type of organism that can reproduce to produce fertile offspring
8
Q
Reproductive success
A
If having a certain allele is advantageous to an individual, it is more likely to survive and thus reproduce
9
Q
What is natural selection?
A
The process by which the frequency of advantageous alleles gradually increases in a populations gene pool over time
10
Q
What is an Anatomical adaption?
A
Structural features that increase the chance of survival
11
Q
What is a Behavioral adaption?
A
The ways in which an organism acts that increase the chance of survival
12
Q
What is a Physiological adaption?
A
Processes inside the body that increase the chance of survival
13
Q
Adaption definition
A
A feature of an organism that increases its chance of survival in its environment
14
Q
What happens to the frequency of advantageous alleles in natural selection?
A
It increases
15
Q
Seasonal breeding is an example of what type of adaption?
A
Physiological
16
Q
Zebra stripes are an example of what type of adaption?
A
Anatomical
17
Q
Being nocturnal is an example of what type of adaption?
A
Behavioral
18
Q
Example of stabilising selection
A
Infant birth rate
19
Q
Example of Directional selection
A
Antibiotic resistance
20
Q
What is a triple codon?
A
A sequence of three bases that codes for an amino acid
21
Q
Directional selection
A
A type of selection that favours individuals that differ in one direction (fall to the left or the right) from the population mean. This changes the traits of the
population
22
Q
Stabilising selection
A
A type of selection that favours individuals close to the mean, maintaining the traits of the population
23
Q
Degenerate definition
A
A feature of the genetic code; more than one triplet can code for a particular amino acid
24
Q
What happens in a substitution mutation?
A
When one base is replaced with another. This may effect one amino acid and therefore the protein shape/function, but they are generally less serious than insertion of deletion mutations
25
What happens in a deletion mutation?
When one nucleotide is randomly deleted from the DNA sequence. This may effect amino acids and therefore the protein shape/functions. A deletion has a knock-on effect (Frame-shift mutation - to the left)
26
What happens in an insertion mutation?
When one nucleotide is randomly inserted into the DNA sequence. This may effect amino acids and therefore the protein shape/functions. An insertion has a knock-on effect (Frame-shift mutation - to the right)
27
What is the order of classification?
```
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
```
28
What is the three Domain system?
Bacteria, Archaea and Eukarya
29
What is the six Kingdom system?
Eubacteria, Archaebacteria, Protista, Plantae, Fungi and Animalia
30
Rules of the Binomial naming system
1. Always in italics
2. If handwritten, it should be underlined
3. Genus requires a capital, species does not
31
Binomial system
A universal system of naming organisms that consists of two parts: the
generic name and the specific name, e.g. Homo sapiens
32
Phylogenetic classification definition
A type of classification that divides organisms into groups based on evolutionary relationships and homologous characteristics. It uses a hierarchy in
which smaller groups are contained within larger groups, with no group overlap
33
Artificial classification definiton
A type of classification that divides organisms into groups based on
analogous characteristics such as leaf shape, number of legs and type of wing
34
What is Courtship behaviour?
The behaviour by which members of a species select reproductive partners. It enables organisms to recognise their own species, identify a mate with a capacity to breed, form a pair bond, synchronise mating and become able to breed themselves
35
Why is it important for organisms to recognise members of their own species?
To ensure fertile offspring
36
Why is the formation of a pair bond important?
A pair bond can lead to successful mating and raising of subsequent offspring
37
Why is synchronised mating important?
To ensure that the sperm and egg meet
38
Why is ability to reproduce important?
To maintain population
39
Biodiversity definition
The variety of genes, species and habitats within a particular area
40
Species diversity definition
A measure of the number of different species and the abundance of individuals in each of these species within a community
41
Ecosystem diversity definition
A measure of the range of different habitats in a particular area
42
Species richness definition
A measure of the number of different species in a community at a given time. It is a measure of species diversity
43
What three components make up biodiversity?
Species diversity
Genetic diversity
Ecosystem diversity
44
Name three examples of conservation
Intercropping, Reduce use of pesticides, Crop Rotation
45
Index of diversity
Describes the relationship between the number of different species and the abundance of individuals in each of these species within a community
46
Prokaryotic DNA
DNA molecules are: shorter, circular, not associated with protein molecules and do not have chromosomes
47
Eukaryotic DNA
DNA molecules are: longer, linear, are in association with histones (proteins) and form chromosomes
48
DNA molecules in mitochondria and chloroplasts of eukaryotic cells
DNA molecules are: shorter, circular, not associated with protein molecules and do not have chromosomes
49
When are chromosomes visible?
When the cell is dividing
50
Structure of a chromosome
Chromosomes first appear as two identical threads (chromatids) joined at a single point (centromere)
51
Chromosome definition
A structure consisting of a long, coiled molecule of DNA and its associated proteins, by which genetic information is passed from generation to generation
52
Chromatid definition
One strand of a replicated chromosome
53
How DNA is packed into a chromosome
1. DNA is in a double helix
2. DNA helix is wound around histones
3. DNA-histone complex is coiled
4. This coil is looped and further coiled before being packed into the chromosome
54
How many DNA molecules are in a single chromosome?
One
55
Homologous chromosomes definition
A chromosome pair, one paternal and one maternal, with the same gene loci
56
What is a diploid number?
The number of chromosomes within a cell's nucleus
57
What is the human diploid number?
46
58
Homologous chromosomes carry the same genes but they are not genetically identical, explain why
They may carry different alleles of the same gene
59
What is the shape of DNA
Double-helix
60
What is the shape of mRNA?
Single-helix
61
What is the shape of tRNA?
Clover-leaf
62
What is the sugar in DNA?
Deoxyribose
63
What is the sugar in mRNA?
Ribose
64
What is the sugar in tRNA?
Ribose
65
What are the bases in DNA?
Adenine
Thymine
Guanine
Cytosine
66
What are the bases in RNA?
Adenine
Uracil
Guanine
Cytosine
67
Location of DNA
The nucleus
68
Explain which organelle is required for protein synthesis and where it is located
Ribosomes – in cytoplasm and on the rough endoplasmic reticulum
69
Why is the production of mRNA required?
DNA cannot leave the nucleus and protein synthesis has to happen in cytoplasm
- Too large
- may get damaged
- Codes for all proteins –> not all cells
need to make all of them
70
Describe the difference between pre-mRNA and mRNA and explain why mRNA being smaller is useful
Pre-mRNA contains exons and introns mRNA contains exons and is smaller to leave nuclear pore
71
Explain which part of the pre-mRNA codes for protein and which is non-coding
Exons – codes for proteins
| Introns – non-coding
72
Suggest why prokaryotes transcribe DNA but do not need to splice
Prokaryotic mRNA contains only exons
73
Location of RNA
Manufactured in the nucleus but found throughout the cell
74
Chemical stability of DNA
Chemically very stable
75
Chemical stability of mRNA
Less chemically stable than DNA and tRNA
76
Chemical stability of tRNA
More chemically stable than mRNA but less chemically stable than DNA
77
How many polynucleotide chains are in DNA?
Double polynucleotide chain
78
How many polynucleotide chains are in RNA?
Single polynucleotide chain
79
Size of DNA compared to mRNA and tRNA
Largest of the three
80
Size of mRNA compared to tRNA and DNA
Smaller than DNA, larger than tRNA
81
Size of tRNA compared to DNA and mRNA
Smallest of the three
82
What is the role of RNA polymerase during transcription?
To join the complimentary free RNA nucleotides to form mRNA
83
How is mRNA produced in the nucleus of a cell
1. DNA Helicase breaks hydrogen bonds (unzipping the DNA).
2. Only one strand of DNA will act as a template for transcription
3. Complimentary free RNA nucleotides are attracted to the exposed bases
4. RNA polymerase joins the RNA nucleotides, building mRNA
5. Pre-mRNA is spliced to remove introns
84
What is the function of mRNA?
To act as a template for protein synthesis
85
Suggest how the structure of tRNA makes it adapted for protein synthesis
Contains an anticodon that codes for a specific amino acid. These help to form the correct chain of amino acids to make a protein
86
Name the cell organelle involved in translation
Ribosome
87
Describe the role of tRNA in the process of translation
A tRNA molecule attaches an amino acid at end and has a sequence of three bases called an anticodon. The tRNA molecule is transferred to a ribosome on an mRNA molecule. The anticodon on tRNA pairs with the complementary codon sequence on mRNA. Further tRNA molecules, with amino acids attached, line up along the mRNA in the sequence determined by the mRNA bases. The amino acids are joined by peptide bonds. Therefore the tRNA helps to ensure the correct sequence of amino acids in the polypeptide chain
88
Anticodon definition
A sequence of three nucleotide bases at one end of a tRNA molecule that is specific to an mRNA codon
89
Mean definition
The average of a set of numbers calculated by dividing the sum of the values by the number of values
90
Cellular proteome
The proteins expressed in a given type of cell
91
Chromosome mutation definition
A change to the number or structure of chromosomes that can occur spontaneously
92
Classification definition
The organisation of organisms into groups. There are two types of classification: artificial and phylogenetic
93
Codon definition
A sequence of three bases on mRNA that codes for a specific amino acid
94
Conservation definition
The maintenance of ecosystems and biodiversity by humans in order to preserve the Earth’s resources
95
Exon definiton
A sequence of DNA that codes for an amino acid sequence
96
Fertilisation definition
The random fusion of haploid gametes during fertilisation to produce a diploid
zygote. Genetic information is mixed, creating genetic variation
97
Gene mutation definition
A change to at least one nucleotide base in DNA or the arrangement of bases. Gene mutations can occur spontaneously during DNA replication
98
Generic name definition
Denotes the organism’s genus. The first letter is written in uppercase, e.g. Homo
99
Genetic code definition
The rules by which triplets in a DNA base sequence code for the sequence of amino acids in a polypeptide chain. The genetic code is degenerate, universal and non-overlapping
100
Genome definition
The entire set of genes in a cell
101
Histones definition
Proteins that, together with DNA, form chromosomes in the nuclei of eukaryotic cells
102
Independent segregation definition
The random separation of homologous chromosomes in meiosis 1 that produces genetic variation
103
Intron definition
A non-coding sequence of DNA
104
Locus (Loci) definition
The position of a gene(s) on a chromosome
105
Meiosis definition
A type of cell division that produces four genetically different daughter cells (gametes) with a haploid number of chromosomes. It involves two divisions
106
Mitosis defintion
A form of cell division that produces two genetically identical diploid daughter cells
107
Mutagentic agent definition
An agent that increases the rate of gene mutations above normal level
108
Non-coding sequence
A sequence of DNA that does not code for an amino acid sequence e.g. repeating base sequences and introns. Non-coding sequences make up significant
portions of eukaryotic nuclear DNA
109
Non-disjunction definition
A change in the number of chromosomes due to the failure of homologous chromosomes to separate during meiosis. This may result in a gamete with one more or one less chromosome
110
Non-overlapping definition
A feature of the genetic code; each base in a sequence is read once and is only part of one triplet
111
Random Sampling
A sampling technique used to avoid bias e.g. creating a square grid and generating random coordinates
112
Recombination definiton
When broken-off pieces of chromatid combine with another chromatid on a different chromosome during crossing over
113
Crossing over definition
The process in meiosis 1 in which homologous chromosomes pair up, their chromatids wrap around one another and their alleles are exchanged at equivalent portions of chromatids. This creates genetic variation
114
Ribosome definition
Sub-cellular structures where protein synthesis takes place. Ribosomes consist of a small subunit and a large subunit
115
Specific name definition
Denotes the organism’s species. It is written in lowercase letters, e.g. sapiens
116
Splicing definiton
The process following transcription in eukaryotic cells in which introns are removed from pre-mRNA and exons are joined together to form mRNA
117
Standard deviation (normal distribution curve) definition
A measure of the width of a normal
| distribution curve and an indication of the range of values
118
Mean (normal distribution curve) definition
A measure of the maximum height of a normal
| distribution curve
119
Taxon definition
Each group within a phylogenetic classification system
120
Transcription definition
The formation of pre-mRNA in eukaryotes and mRNA in prokaryotes from a section of the template strand of DNA. It is the first stage of protein synthesis
121
Translation definition
The second phase of protein synthesis that takes place in the ribosomes. mRNA is used as a template for the attachment of tRNA molecules with complementary anticodons. The amino acids carried on adjacent tRNA molecules are joined to form a polypeptide chain
122
Universal definition
A feature of the genetic code; the code is the same in almost all organisms. This is evidence for evolution
123
Variation definition
The differences between individuals due to genes, the environment or a combination of both
