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topic 4 (genetics ,biodiversity,classification) Flashcards

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1
Q

what is a gene?

A

A section of DNA that codes for amino acids in polypeptides and functional RNA . these polypeptides make up proteins/enzymes.Genes are located in the locus.

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2
Q

what is the minimum amount of bases that code for an amino acid?

A

3 as their are minimum amount of 20 amino acids.4 squared is 16 which is insufficient

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3
Q

what is a triplet?

A

3 nucleotide

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4
Q

what is degernate code?

A

when the amino acid can be coded by more than 1 triplet.this is beacause a total of 4^3=64 amino acids but the genome only codes for 20 amino acids

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5
Q

explain why degenerate code is an advantage?

A

if their is a point mutation (mutation of one base) the triplet is still likely to code the same amino acid

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6
Q

what is non overlapping?

A

Each base is only read once in its triplet.

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7
Q

advantage of non overlapping DNA?

A

If their is a mutation it will only affect the codon and one amino acid

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8
Q

what does universal code mean?

A

triplets code for the same amino acid in all organims and this is evidence and this is evidence for evolution

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9
Q

explain how a change in one base may result in an enzyme be non functional?

A

a change in amino acid will affect the primary structure.This will then all affect the tiertary structure.A change in the tiertary structure can affect the active site of the enzyme.A change in the active site will mean it wont bind to the complementary substrate.Thus the enzyme substrate complex not being made.

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10
Q

what are coding and non coding coding sequence?

A

coding genes -exons

non coding genes-introns

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11
Q

the difference between DNA in eukaryotes and prokaryotes?

A

DNA is linear and larger in Eukaryotes.it is also associated with histones to make chromosomes
the chloroplast and mitochondria have their own DNA but it is like prokaryotic
DNA is circular and shorter in prokaryotes

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12
Q

what is an allele?

A

The different forms of a gene
each individual inherits one allele from each parent.
A change in the base sequence (mutation) will produce a completely new gene

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13
Q

what is a chromatid?

A

When DNA first replicated in mitosis it produces a two strand structure.Each thread is a chromatid

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14
Q

what is a homologous pair?

A

A pair of chromosomes one maternal one paternal that have the same gene loci
e.g a homologous pair can contain the gene tongue rolling but one allele may be non roller and the other one roller allowing only the dominant one to be expressed

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15
Q

what is a haploid and diploid?

A

haploid-half the set of chromosomes

diploid - full set of chromosomes

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16
Q

what is the genome?

A

the complete set of genes in a cell

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17
Q

what is a proteome?

A

the complete set of proteins produced by the genome

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18
Q

what is the structure of RNA

A

It is made up of a pentose sugar called ribose
A nucleotide base (Adenine ,Guanine ,Cytosine,Uracil)
Phosphate group
it is single stranded

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19
Q

explain the use of trna in protein synthesis?

A

it is a single stranded and clover shaped.One side is the attachment point which attaches to amino acids.The other attached to the codons of the mrna.The trna has the anticodon that is made from complimentary bases
each trna is specific to one amino acid and has the anticodon for it

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20
Q

explain the use of mrna in protein synthesis?

A

Mrna is produced via transcription.It then moves out the nucleus envelope via the nuclear pores.In the cytoplasm it associates with ribosomes. It is perfect as it stores the bases in codons which are complimentary to the triplet in DNA and these can be used in protein synthesis

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21
Q

the similarities and difference between mrna and trna

A

trna is clover shaped,mrna is straight single helix chain
mrna is large, trna is small
both contain ribose
both have the same bases (Adeine ,guanine,cytosine,uracil)

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22
Q

what is transcription?

A

the process of making pre-mrna using dna as a template

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23
Q

describe transcription?

A

DNA helicase breaks the hydrogen bonds between nucleotide base in DNA exposing the nucleotide
One strand acts as the complimentary strand
RNA polymerase joins nucleotide complimentary to the template strand from the nucleus pool.This forms the pre MRNA single strand.
This continues until the RNA polymerase reaches the stop triplet code.
the DNA code rebinds

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24
Q

what is splicing?

A

removing non coding triplets (introns) as these prevent the production of polypeptides allowing the exons to line up. Done via the protein splicosome.
This is mainly in eukaryotes as prokaryotes dont have introns

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25
what are histones?
proteins that provide structural support to chromosomes
26
why is splicing necessary?
splicing removes introns which are non coding in the pre mrna. If left in these will lead to the production of non functional polypeptides
27
describe the process of translation (protein synthesis)
Mrna attaches to the ribosome at the start codon Trna has the complimentary anticodon it brings the amino acid specific to this . It works in twos the 2 amino acids are peptide bonded requiring enzyme and ATP . this process continues until the stop codon which does not have an amino acid allowing the ribosome to deattach breaking the peptide chain
28
why cant DNA exit the nucleus instead of mrna?
DNA is too big to leave the nucleus. There are also harmful enzymes in the cytoplasm which could damage enzyme
29
what is a gamete?
sex cell e.g female egg cell,male sperm cell
30
what is a mutation?
A change to a nucleotides base/bases in DNA
31
when is a mutation likely to occur?
Formation of gametes | DNA replication
32
describe substitution mutation and explain its effect
In the DNA one of its nucleotides is swapped for another. This can cause the production of the wrong amino acid effecting the tiertary structure og the polypeptide required.It can make the protein disfunctional. However due to DNA being degenerate their is a chance of the same amino acid being produced
33
describe deletion mutation and explain its effect?
This is a deletion of a nucleotide from the DNA. As DNA is read in triplets it causes all the other nucleotides to shift the left changing every single base after.This has a bigger effect than subsitution and DNA is less likely to produce the correct functional polypeptide
34
what mutation effects chromosome number
non disjunction mutation - polyploidy -changes in whole set aneuploidy changes in individual number of chromosomes
35
describe polyploidy?
changes in whole sets of chromosomes occur when organims have three or more sets of chromosomes
36
why is mutations in DNA replication worse than mutations in transcription?
Mutations in replication are inherited and have a permanent effect on the whole organism Errors in transcription are temporary and only affect specific cells making them less damaging
37
what increases the rate of mutations?
Mutagenic agents
38
what does meiosis produce?
4 haploid daughter cells that are genetically different
39
why is meiosis important?
If meiosis did not occur the chromosome number of a species would keep doubling every new generation. Meiosis allows it to remain constant.
40
when does meiosis mostly occur?
in animals it mainly occurs in the formation of gametes
41
describe the stages of meiosis?
meiosis-1 prophase -1
42
Explain the process of meiosis
start of with a diploid parent cell (meiosis 1 )first nuclear divisions leaves 2 daughter cells (meiosis 2) second nuclear divisions leaves 4 daughter haploid cells
43
what stage of meiosis does independent segregation and crossing over occur?
meiosis 1 prophase 1
44
describe independent segregation and explain how it causes variation?
in meiosis 1 anaphase 1 the homologous pairs of chromosomes line up at the cell equator. the order in which they line up is random.The pairs are seperated so one of each chromosome ends up at the daughter cell.
45
describe and explain how crossing over produces variation?
in meiosis 1 prophase 1 homologous chromosomes line across the equator.parts of the chromatids can twist of each other.this puts tension on the chromatid and it can break off. In recombination the broken part can join the other chromatid. This makes new combination of alelles on the chromatid.
46
what are the three ways variation occurs in meiosis?
independent segregation crossing over fusing random gametes
47
formula for variation?
(2^n)^2 n= paris of homologous chromosomes does not include crossing over
48
if an animal has an odd number chromosomes explain why it cannot produce offspring?
Gametes are produced via meiosis. An odd number of chromosomes mean the homologous pairs can not pair up properly.this prevents meiosis and thererfore the production of gametes required for fertilisation
49
define genetic diversity?
total number of different alleles in a population
50
define population?
A group of individuals that live in the same place,are the same species and can interbreed
51
explain how reproductive success affects allele frequency?
within a species of a population their is a gene pool containing a wide variety of alleles.Mutations can occur. Some of these mutations will create advantageous alleles that are better suited to the environment. The animals with these advantageous alleles survive competition and can reproduce successfully increasing the amount of the population with this allele.This is at the expense of the animals without the allele.
52
describe selection?
selection is the process by which organisms better adapted for the environment survive and breed while the organisms not suited die out.
53
describe the two types of variation?
directional selection- favours individuals that vary in one direction from the mean of the environment changing the characteristics of the population stabilising selection-preserves the characteristics of the population
54
example of directional selection?
bacteria is killed by penicillin.A mutation in bacteria produced an enzyme that killed penicillin. This meant the bacteria without the enzyme died.However the bacteria with it could survive and reproduce via binary fission. The population of penicillin resistant bacteria increased at the expense of the non resistant bacteria.Over time their was directional selection showing a shift in the resistance of bacteria.
55
formula for working out the amount of different types of gametes?
the possible combinations can be meaured as 2^n where n is the number of homologous pair chromosomes
56
what is classification
the organisation of living organims into groups
57
define species?
organsims that can reproduce together to produce living fertile offspring
58
explaining the binomial system?
naming system used universally first name is the genus (first letter is capital) second name is the species (all lowercase) all in italics if printed if written underline.
59
what is courtship behaviour?
Members of the same species display the same behaviour. this allows them to distinguish each other. This behaviour is genetically determined.courtship behaviour is essential for the survival of a species.
60
what does courtship behaviour help to achieve?
recognise same species find potential breeding partner pair bond (lead to successful mating and raising of offspring) synchronise mating (it takes place when their is maxiumum probability of the sperm and egg meeting)
61
when are females open to mating?
they are receptive to mating around the period they produce eggs. Courtship behaviour is used to check if they are at their receptive stage.
62
what are the 2 types of biological classification?
artificial - based on features e.g colour,size number of legs phylogenetic- based on evolutionary relationship between ancestors and organism classifies species into organsims based on shared characteristics derived from ancestors arranged in a hierachy which groups are contained in larger composite groups with no overlap
63
what is a taxon?
a single group in the hierachy
64
list the whole hierachy?
``` domain kingdom phylum class order family genus species ```
65
what are the three types of diversity
species diversity- The amount of different species and the population of each in a community genetic diversity- the different number of genes individuals possess that make up the population of a species ecosystem diversity-the range of diffeent habitats
66
why are agricultural and natural ecosystems different in biodiversity?
Agricultural ecosystems are controlled by humans.Farmers select specific species for particular qualities that make them more productive.This reduces genetic variety of alleles.This produces competiton for other species which most will not survive
67
explain the reason for pestercides?
Exclude species that could potentially act as competition for light, water and food for the desired species in the ecosystem. This results a reduced species diversity
68
direct practices that directly removed habitats and reduced species diversity
removal of hedgerows and grubbing out woodlands creating monocultures e.g removing natural meadows with cereal crops filling in ponds , marshes and other wetlands overgrazing of land
69
indirect practices that have a impact on habitats and species diversity?
Use of pesticides and inorganic fertilisers escape of affluent from silage stores absence of crop rotation and lack of intercropping
70
what is intercropping
growing 2 or more crops within the close proximity(same field)
71
list conservation techniques that can combat lack of diversity?
maintaining hedgrow at most beneficial height and shape (a) plant hedges as boundaries rather than fences mainting existing bonds and creating new ones leave wet corners of fields rather than draining them planting native trees on land reducing use of pesticide using biological control and organic fertilisers
72
what are the limitations of comparing observable characteristics to establish genetic variety?
Characteristics are based on multiple genes(polygenic) | characteristcs can also be based on environmental factors
73
how is genetic diversity checked now?
Comparing base sequences in DNA. this happens via computer systems where each nucleotide can be tagged with different colours.This allows different DNA sequences to be compared. species closely related will have more DNA bases similarities MRNA strands can also be compared For proteins the difference in amino acid chains can also be compared between 2 species
74
what is the difference between intraspecific/interspecific variation?
interspecific variation- when difference species differ | intraspecific variation - when within species their is differentiation
75
what is the difference between intraspecific/interspecific variation?
interspecific variation- when difference species differ | intraspecific variation - when within species their is differentiation
76
what is sampling?
taking individual measurements from the population of organisms being being investigated
77
what are the problems with sampling?
sampling bias-the investigators may be making unrepresentative choices either consciously or unconsciously. chance-through chance it may be unrepresentative
78
what is the best method in sampling?
random sampling Divide the area into a grid using 2 tape measures at right angles use random number generator to obtain coordinates take samples at each coordinate
79
what is the best way to minimise chance in random sampling?
large sample size | analysing data collected
80
what is a hierachy?
a group within a group with no overlap
81
assumptions made when using mark release recapture method?
no immigration birth rate is equal to death rate no loss due to predation
82
what
83
what

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