Topic 4 - Genetic information, variation and relationships between organisms Flashcards
(122 cards)
1
Q
What is the structure of a chromosome
A
Two sister chromatids connected by a centromere
2
Q
What is DNA associated with to form a chromosome
A
Histone proteins
3
Q
What feature of chromosomes means they can store lots of genetic information
A
Coiled and loops
4
Q
Define homologous chromsomes
A
A part of chromosomes, one maternal and one paternal, with the same loci at the same positions
5
Q
Define haploid
A
Cells containing one dpi of each chromosome (only 23 chromosomes)
6
Q
Define diploid
A
Cells containing both sets of chromosomes (46 chromosomes)
7
Q
Gene
A
A section of DNA coding for a particular polypeptide or functional RNA
8
Q
Allele
A
An alternative form of a gene
9
Q
Locus
A
The position of the gene on the chromosome
10
Q
What are 2 names for 3 nitrogenous bases in a gene
A
Triplet or codon
11
Q
What does a triplet code for
A
An amino acid
12
Q
How many combinations of triplets can there be
A
64
13
Q
How many amino acids is there
A
20
14
Q
What does the phrase non-overlapping mean
A
Each base in the sequence is only read once
15
Q
What des the phrase degenerate mean
A
Each amino acid is coded by more than one triplet
16
Q
What does the phrase universal mean
A
Each triplet codes for the same amino acid in all organisms
17
Q
What does the fact that triplet codes are universal lead to
A
indirect evidence for evolution
18
Q
What is the genome
A
All the genetic information in a cell or organism
19
Q
What is the proteome
A
All the proteins that a cell or organism can produce
20
Q
What is protein synthesis
A
The production of polypeptides from information stored in a cells DNA
21
Q
What are the 3 types of RNA
A
mRNA, tRNA, rRNA
22
Q
What does mRNA stand for
A
Messenger RNA
23
Q
What does tRNA stand for
A
Transfer RNA
24
Q
What process is mRNA involved in
A
Transcription
25
What process is tRNA involved in
Translation
26
What happens in transcription
A copy of the gene is made into mRNA
27
What happens in translation
mRNA binds to a ribosome and the genetic code is converted into a sequence of amino acids to make a protein
28
What are some features of mRNA
-single stranded helical shape
-sequences of codons code for an amino acid
-moves into the ribosome acts as a template
-The sequence and length is determined by DNA
29
What are features of tRNA
-single stranded clover shape due to hydrogen bonds between nitrogenous bases
-Transports amino acids to the ribosome to form polypeptides
-Contains an anti codon
-Contains a binding site for the protein
30
Which type of RNA contains an anticodon
tRNA
31
Which type of RNA contains an single stranded helical shape
mRNA
32
Which type of RNA contains a clover like shape
tRNA
33
Which type of RNA acts as a template for protein synthesis
mRNA
34
Where does transcription take place in eukaryotic cells
nucleus
35
Where does transcription take place in prokaryotic cells
cytoplasm
36
What enzyme is used in transcription
RNA polymerase
37
What does RNA polymerase do in the first step of transcription
The hydrogen bonds between nitrogenous bases are broken to reveal the template strand
38
What happens to the template strand
free RNA nucleotides binds and RNA polymerase forms phosphodiester bonds to form mRNA transcript
39
what stops the RNA poymerase
a terminator sequence
40
What happens after the terminator sequence
DNA is reformed and pre mRNA is formed
41
How does pre mRNA turn into mature mRNA
splicing
42
What two types of regions are their in pre mRNA
exons and introns
43
what is an exon
an expressive region (coding)
44
What is an intron
An interrupting region (non-coding)
45
What type of regions does mature mRNA contain
exons only
46
Where does the mature mRNA leave through
nuclear pores
47
What does translation produce
a poly peptide
48
what are ribosomes made from
proteins and rRNA
49
what does the mRNA bond to at the start of translation
A ribosome
50
what is at the start of every mRNA
a universal start codon
51
What does tRNA carry
A specific amino acid
52
how does the tRNA bind to the mRNA
Through complementary base pairing between the codon and anticodon
53
what type of bond are formed between the amino acids
peptide bond
54
What type of reaction forms polypeptides
condensation
55
what stops the formation of the poly peptide chain
A stop codon
56
What is required for the condensation reaction to take place and form a poly peptide
ATP
57
how many bases code for an amino acid
3 bases (a codon)
58
What are the two types of mutations
Gene and Chromosome
59
What are gene mutations
When a nucleotide is substituted in or deleted from the gene
60
What are chromosomes
Change in the number or structure of chromosomes
61
What can substitution mutations lead to and why is this less harmful,
Silent mutations since the genetic code is degenerate a change will not necessarily lead to a change I amino acid
62
What do deletion mutations lead to and why is this more harmful
Frame shift meaning a complete change in the codons so different Amino acids so diff 1 structure so diff 3 structure meaning different function
63
what are the causes of gene mutations
ionising radiation, errors in DNA replication, mutagenics such as chemicals and viruses
64
what are the causes of chromosome mutations
non disjunction during meosis
65
What is a diploid cell
Has two of each chromosome
66
What is a haploid cell
Has one of each chromosome
67
Fertilisation
When the nucleus of the male and female gamete fuse
68
Zygote
A fertilised egg
69
First step in meiosis
There are homologous pairs of chromosomes
70
Homologous pair
One maternal one paternal which the same genes in the same loci
71
second step in meiosis
Chromosomes replicate forming sister chromatids held together by a centromere
72
third step in meiosis
homologous pairs line up and crossing over occurs
73
crossing over
When a chromatid breaks and rejoins with its homologous pair
74
fourth step in meiosis
homologous pairs randomly separate into two daughter cells (independent segregation)
75
Independant segregation
random combinations of chromosomes
76
5 step in meiosis
Sister chromatids spilt and cell divides
77
Final step of meiosis
4 genetically different haploid cells
78
What is the cause of variation in both sexual and asexual reproduction
Mutation
79
What are the causes of variation in only sexual reproduction
Crossings over, independent segregation and random fertilisation
80
What is genetic diversity
The total number of different alleles in a population
81
What is a gene pool
The total number of alleles in a population
82
What can genetic diversity be increased by
Mutations and migration (intro of new alleles)
83
How do you work out the number of combinations
2 to the power of n where n is the number of chromosomes
84
What do advantages alleles increased over time
greater chance of survival and reproduction as alleles are passed on to offspring so allele frequency in the gene pool increases
85
what is selection
The process by which better adapted organisms will survive to reproduce and pass on genes
86
What are the three types of selection
directional, stabilising and (distributive)
87
What is directional selection
When an extreme phenotype is selected for over other types.
88
What is an example of directional selection
Antibiotic resistance, giraffe necks
89
When does directional selection occur
When there is a mutation giving a selection advantage and when there is a sudden change in environmental conditions
90
What is stabilising selection
When the mean phenotype is selected for over extreme phenotypes.
91
When does stabilising selection occur
When the environment is more stable
92
What are examples of stabilising selection
Bird number of offspring
Birth weight
93
What is taxonomy
The theory and practice of biological classification
94
What are the 8 components of the classification hierarchy
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species (Kids playing chicken on freeways go splat)
95
How do we know it is a classification hierarchy
Each organism is in one group and there is no overlaps and there are smaller groups within larger groups
96
What is each tier of the hierarchy known as
Taxa
97
What is binomial meaning
Two names
98
What language is the binomial system based on
Latin
99
What are the rules for the binomial system
The generic name (genus) starts with a capital and the specific name (species) starts with lowercase. The whole name is in italics
100
Why is the binomial system important
So scientists know they are referring to the same organisms
101
What is phylogeny
the evolutionary relationship between organisms and their common ancestors
102
Who's theory is it that all organisms evolved from a common ancestor
Charles Darwin
103
What is courtship behaviour
Signals organisms use to recognise individuals of the same species and if they are prepared to mate
104
Why is courtship behaviour important
- individuals of the same species are recognises
- Identifying mates capable of breeding
- Form a pair bond (to raise offspring)
- Synchronise mating ( max probability of sucessful fertilisation)
- Becoming sexually mature
105
What is biodiversity
The number and variety of living organisms in a certain area
106
What 3 factors affect biodiversity
Species, genetic and ecological diversity
107
What is species richness
The number of different species in an area ata given time
108
What is the equation to find the index of diversity
d=N(N-1)/sigma n(n-1)
109
What do the letters in the index of diversity equation stand for
d=index of diversity
N=number of organisms of all species
n=number of organisms of each species
sigma= sum of
110
What does the d value tell us
The greater the d value the greater the species diversity
111
Why is the d value better than qualitative measures
It gives a quantitative measure, whereas qualitative measures are subjective
112
What are limitations of the d value
Biomass isn't taken into account
Can be difficult to distinguish if a plant is one organism or multiple (moss)
113
What is agriculture needed for
food, fibres,jobs, medicines, biofuels
114
What is yield
The maximum produce that can be made in an area
115
Name 5 farming methods
-Hedgerow removal
-pesticides/herbicides
-fertilisers
-draining marshlands
-monoculture
116
Impact on biodiversity of hedgerow removal
Habitats destroyed and replaced by a single organism
117
Impact on biodiversity of pesticides/herbicides
Can lead to bio accumulation
118
What is bioaccumulation
Where pesticides or herbicides are eaten by animals at the bottom of the food chain and not digested properly thus are stored in their fat and eaten by predators which then are killed by the chemicals.
119
Impact on biodiversity of fertilisers
Leads to eutrophication
120
What is eutrophication
When fertilisers are washed into water sources leading to over growth of algae leading to no sunlight oxygen for marine organisms beneath the algae.
121
Impact on biodiversity of draining marshlands
removes large habitats which decreases biodiversity
122
Impact on biodiversity of monoculture crops
low biodiversity so less stable ecosystems as they are reliant on one food source.
