DNA Flashcards
1
Q
gene
A
base sequence of dna that codes for the amino acid sequence of a poly peptide or a functional RNA
2
Q
Locus
A
a place on a chromosome where a gene is found
3
Q
allele
A
different version of the same gene
4
Q
what do chromosomes exists in
A
homoglous paits
5
Q
homoglous pairs
A
carry the same gene
6
Q
genome
A
entire genetic material in an organism
7
Q
introns
A
non coding regions of dna
8
Q
exons
A
coding regions for making proteins
9
Q
dna shape in eukaryotes
A
long and linear
10
Q
dna shape in prokaryotes
A
circular and short
11
Q
what two organelles contains their own dna
A
mitrocondria and chloroplasts
12
Q
how is the dna in mitocondria and chloroplasts
A
short and circular
13
Q
what is the charge of dna and why
A
negative due to the phosphate ion that’s negatively charged
14
Q
prokaryotes
A
Single celled organism with no membrane organellles
15
Q
Similarities in eukaryotes and prokaryotes dna.
A
Double stranded
Phosphodiester bonds
Phosphate ion
Negative dna
Ribose sugar
16
Q
Differences in dna eukaryotes and prokaryotes
A
Linear vs circular
Nucleus vs cytoplasm
Histone vs none
Long vs short
17
Q
Genetic code is… 3 things
A
Universa
Non overlapping
Degenerate
18
Q
Benefit of genetic code being universal
A
Same in every living organism which allows you to compare genes
19
Q
Non-overlapping genetic code advantages
A
Each triplet is only read once
20
Q
Degenerate advantage for universal code
A
Múltiple triplets code for the same amino acid so less likely to change the structure
21
Q
How can mutations affect proteins and an example
A
Change the bonds and interactions from the variable group
Etc active site on an enzyme
22
Q
Why does transcription happen
A
Dna cannot directly move from nucleus to ribosomes bc it is too big so a copy (messenger rna) of each gene is sent
23
Q
What is mRNA
A
A short strand of rna
24
Q
Differences between dna and rna
A
Hydrogen bonds vs none
Long vs short
Double vs single stranded
Deoxyribose vs ribose
Thymine vs uracil
25
Transcription process
1- hydrogen bonds are broken, unwinding the dna double helix by rna polymerase
2-free rna nucleotides line up against exposed based pairs
3- rna polymerase creates phosphodiester bonds between adjacent nucleotides making pre mRNA
(Eukaryotes) removes introns from pre-mRNA to make mature mRNA called splicing
26
What is the extra step of transcription that eukaryotes do
Splicing- removes introns from pre-mRNA to make mature mRNA
27
Structure of tRNA
Single stranded clover leaf structure that forms hydrogen bonds with itself
28
What are anticodons complimentary to
Codons
29
Translation stages
1- mRNA binds to a ribosome
2- two tRNA arrive at the ribosome carrying specific amino acids. Hydrogen bonds form between the codons and anticodons
3- peptide bonds form between amino acids by condensation reaction that uses ATP
4- one tRNA leaves and the ribosome moves to the next codon
5- next tRNA bid and forms another peptide bonds
6-process repeats until a stop codon is reached
30
What step uses ATP in translation
Condensation reaction between amino acids forming peptide
31
Gene mutation
Change in the base sequence of dna in a chromosome that creates a new allele
32
Substituion mutation
Involves one or more base being swapped for a new base which can change the sequence of amino acids
33
What two things can substitution mutations cause
New sequence of amino acids
Early stop code
34
Additional mutation
Ads an extra base to the base sequence
35
Deletion mutation
Deleting/removing a base
36
What is a frame shift
Change to all triplets in a sequence
37
Diploid
Two copies of the same chromosome
38
Haploid
One copy of each chromosome
39
Mitosis and meiosis differences
One division vs two
Two daughter cells vs four
Diploid daughter cells vs haploid daughter cells
Genetically identical vs genetically different
40
Mitosis and meiosis similarity
Both involve dna replication
41
Meiosis steps
Diploid parent cell
DNA replicates
Chromosome homogenous pairs line up down equator
Cell divides into two and is haploid
Cel divides again with sister chromosomes separating forming four genetically different haploid daughter cells
42
How many ways does meiosis cause genetic variation
Four
43
What four things cause genetic variation in meiosis
Mutations
Independent assortment
Random fertilisation
Cross overs
44
What is random fertilisation
When egg and sperm merge after meiosis
45
What are cross overs
When two separate chromosomes become bivalent and cross over forming a chias which swaps the alleles on the chromosome
46
Independent assortment
Homoglous chromosomes line up down t equator randomly leading to different allele combinations
47
Equation for homoglous pairs possible combinations
2 to the power of n
Or
2 to the power of the number of pairs
48
How is Down syndrome caused
An extra copy of chromosome 21
49
What is the process called that leads to an extra copy of chromosome 21
Non-disjunction
50
What happens in 1-meiosis disjunction
Chromosome does not separate properly in the first division
51
What happens in 2-meiosis non-disjunction
Sister chromatids ont separate properly on the second division
52
Genetic diversity
Total number of alleles in a population
53
Why is genetic diversity good
Prevents extinction of species from diseases
54
Natural selection
Random mutation creates new allele giving the animal an advantage
More likely to survive from more food etc
Reproduce and pass on allele
Repeats over many generations and increases allele frequency
55
Stabilising selection
Environmental conditions are the same and well adapted organisms are favoured
Extreme phenotypes are selected against
56
Directional selection
Environmental conditions change and extreme phenotypes are favoured
57
Stabilising selection graph
Increases on the mean phenotypes
58
Direction selection graph
Shifts towards extreme phenotypes
59
What type of selection does antibiotic resistance show
Directional
Unmutated phenotypes die out
60
Standard deviation
Statistic
How spread out results are around the mean
61
Circle around antibiotics on bacteria
Zone of inhibition
62
Divisions by mitosis method
Log2 (number of bacteria). Timed by minutes if there
63
Error bar
Mean +2 sd and then -2sd
64
Species
Can produce fertile offspring
65
Are body cells haploid or diploids
Diploid
66
Why are two non species offspring infertile
They don’t have homogenous pairs that can line up
Often have an odd number of chromosomes
67
How do organisms recognise others of the same species
Courtship behaviour
68
What is courtship behaviour
Attracts the same species but opposite gender and forms. Bond to produce fertile offspring
69
Classification hierarchy
Domain
Kingdom
Phylum
Class
Order
Family
genus
Species
70
How are organisms classified
Based on evolutionary origins and relationships called phenogenetics
71
How to compare organisms
Physical appearance
Courtship behaviours
DNA sequence
Antibody variable regions
72
What do aseptic techniques prevent
Misdiagnosis
73
Why is ethanol used with cells
Breaks down cell membranes by dissolving lipids
74
Habitat
Where organisms can live
75
Biotic
Living factor that affects organisms
76
Abiotic
Non living factor that affects organisms
77
Population
Individuals of the same species in the same area
78
Community
Different species living in the same area
79
Ecosystem
A community and its interactions with abiotic factors.
80
Why is everything in an ecosystem interdependent
Depend on each other for food etc
81
Why does a higher biodiversity make a more stable ecosystem
Because there is greater diversity in the food chain
82
What can all insects do
Pollinate
83
Species richness
Number of different species in an ecosystem
84
Why is species richness a bad way of finding diversity
Only tells you have many species not how many are in within the species
85
What is better than species richness
Index diversity
86
Diversity index equation
Number of organisms X number -1
Sum of all species times -1
87
Human impacts of biodiversity decreasing
Deforestation
Pollution
88
How doe deforestation affect biodiversity
Less habitats
89
How does pollution affect biodiversity
Fossil fuels are used, greenhouse gasses released an ice caps melt so less habitats
90
Why. Are farmers encouraged to re-plant hedges are their fields
More habitats for bees but it men’s less room for them to grow plants
91
Why do farmers use fertiliser and how does it harm biodiversity
So plants have more minerals to grow quicker
Causes eutrophication
92
Eutrophication
Enters lakes and rivers
Algae grows rapidly over the surface
Blocks sunlight for plants
No photosynthesis
No O2 releases
Fish can’t respire and die
93
Why do farmers reuse the same fields and how does it affect biodiversity
Since it’s cheaper
Reduces soil minerals so no other plants can grow
94
Why do farmers introduce non native preditor’s to kill pests and how does this affect biodiversity
To prevent pests eating crops to increase yield
Other native species are killed causing extinction
95
Why do farmers remove hedges and how does it affect biodiversity
So they have more field space to grow crops
But it destroys habitats
96
What is a herbicide
Weed killer
97
Why do farmers use herbicide and how does it affect biodiversity
So weeds don’t compete with their crops for food and minerals
Herbicides kill other plants
