Inheritance Flashcards
1
Q
what is the function of nucleus
A
it controls cell activities
2
Q
what does nucleus contain
A
genetic information - DNA
3
Q
why is DNA a polymer and what is DNA’s structure called
A
because it is made out of monomers called nucleotides
and the structure is called double helix
4
Q
how long are DNA’s in your cell
A
2m
5
Q
which cells are an exception for the given size and give reasons
A
red blood cells because they do not have no nucleus
sperm and egg cells which only have half the genetic material
6
Q
what are chromosome
A
because DNA is too long it tightly coils into a structure called chromosome
7
Q
where are chromosomes stored
A
in the nucleus
8
Q
what is a gene
A
a small section of DNA
9
Q
what does a gene do
A
codes for a specific sequence of amino acids that makes a specific protein which then codes for a specific characteristic
10
Q
give an example of a specific characteristic
A
eye colour or blood type
11
Q
approximately how many genes do humans have
A
around 20,000
12
Q
where are genes found
A
on chromosomes
13
Q
what is meant by genome
A
organisms entire set of genetic material
14
Q
how many pairs of chromosomes does a human’s genome consist of
A
23
15
Q
how many single chromosomes are there in every type of human body cell
A
46 single chromosomes
16
Q
what are specific advantages of understanding the human genome
A
can identify the gens linked to different types of inherited diseases
can help scientists develop effective treatments
can trace the migration of certain populations of people
17
Q
why did humans develop some differences in their genomes
A
because different populations migrated
18
Q
what is a gamete
A
sex cell
19
Q
how many gametes involved in sexual reproduction
A
2
20
Q
what are the two gametes involved in sexual reproduction
A
sperm cell and egg cell
21
Q
how many chromosomes does each sperm and egg cell have
A
23
22
Q
what does sexual reproduction involve
A
fusion of egg cell and sperm cell
23
Q
what happens when the two gametes fuse together
A
zygote is produced
24
Q
how many chromosomes does a zygote have
A
46
25
what chromosomes can a sperm cell be
x or y
26
what chromosomes can an egg cell be
x only
27
what process turns a zygote into an embryo
mitosis
28
what is the mixing of DNA called
crossing over
29
what is variation
the mixing of genetic information from the two parents which leads to genetic differences in the offspring
30
what are the two gametes involved in flowering plants
pollen and egg cells
31
what type of cell division produces gametes
meiosis
32
how many parent cell involved in asexual reproduction
1
33
what type of cell division is used in asexual reproduction
mitosis
34
what happens to the off springs when mitosis occurs
become an identical clone of the one parent meaning there is no variation
35
which organisms use asexual reproduction
smaller animals and some plants and fungi and bacteria
36
how much energy does does sexual reproduction require compared to asexual reproduction
a lot
37
what is fertilisation
the fusing process of egg cell and sperm cell
38
what is meant by haploid
a cell that has half set of chromosomes
39
what is meant by diploids
a cell that has full set of chromosomes
40
what is meiosis
a process of cell division needed specifically to produce gametes
41
where does meiosis take place in the body
in the sex organs
testes and ovaries
42
when do females undergo meiosis
when they're an embryo
43
what is meiosis needed for
to produce gametes
44
how many cell divisions occur in meiosis
2 cell divisions
45
how many daughter cells are formed during meiosis and how are they genetically
4 daughter cells which are genetically different
46
how is the process of meiosis
the same as mitosis but at the end the 2 daughter cells split to create 4 daughter which are genetically different from one another
47
what is the 23rd pair of chromosomes labelled as
xx or xy
48
what does the 23rd pair of chromosomes determine
sex
49
what do the other 22 matched pairs of chromosomes conrol
characteristics
50
which chromosome causes male characteristics
y
51
which combination allows female characteristics to develop
xx
52
why does a sperm cell have 50 percent chance of having the chromosome x or 50 percent chance of having chromosome y
because when the sperm was being made through meiosis the x and y chromosomes were drawn apart in the first division so each sperm cell gets 50% chance of having a x chromosome or y chromosome
53
what causes there to be different versions of genes
mutations
54
what are alleles
when each gene exists in different forms
55
how many alleles are inherited from each gamete
1 allele inherited from each gamete
56
what are the combination of alleles we inherit known as
genotype
57
what is phenotype
alleles that code for proteins which determine our physical characteristics
58
term used for two different alleles of a gene
heterozygous
59
term used for two same alleles of a gene
homozygous
60
what is meant by homozygous dominant
when only one copy of the allele is needed in order for the protein to express
eg Aa
61
what is meant by homozygous recessive
when two copies of the same allele are needed in order for the protein to express
eg aa
62
what are the two examples of inherited disorders
cystic fibrosis and polydactyly
63
what does cystic fibrosis cause the body to do
causes the body to produce excessive and very sticky mucus in the air passages and pancreas
64
what type of allele causes cystic fibrosis
recessive allele "f"
65
what do you call people that have only one copy of cystic fibrosis allele
carriers
66
why do carriers not suffer from cystic fibrosis
because they only have one copy of the allele meaning that they carry the cystic fibrosis gene but do not suffer from it
67
what do the parents need to have in order for their off springs to carry cf
both need to be carriers of cf or both have to have the disorder themselves
68
what is different about someone who suffers from polydactyly
they have extra fingers or toes
69
what is polydactyly caused by
dominant allele D
70
what is the chance of the off spring having polydactyly if only one of the parents have the condition and why
it is a 50% chance because the allele is dominant meaning the protein will be expressed even if there is one copy of the allele
71
when can embryos be screened for genetic disorders
during ivf
72
how are embryos screened
before implanting the embryo in the womb it is possible to remove a cell from each embryo and analyse its genes
73
what are the against embryonic screening
- prejudice increases as people imply that people with genetic problems are undesirable
- everyone will want to screen their embryos to pick characteristics for their desirable off springs
- it is too expensive
74
what are the for embryonic screening (3 points)
- it will help people stop suffering
- treating disorders costs the gov and tax papers a lot of money
- there are laws stopping people from going too far with embryonic screening
75
what is variation
differences in characteristics between organisms
76
what is genetic variation
the differences in dna sequences between organisms
77
how is genetic variation caused
by the random combination of genes
78
what is inherited variation
variation caused by genes
79
what is environmental variation
variation caused by environmental factors
80
how is environmental variation caused
it is caused by differences in the surroundings or condition an individual experiences
81
give 3 examples each for environmental variation and inherited variation
accent, scar, tattoos
eye colour, blood type, genetic disorders
82
what is mutation
an alter in the sequence of an organism's dna
83
what does a mutation cause
causes genes to alter which will then produce a new allele
84
what will the new allele do
code for a specific protein for a specific characteristics
85
what happens when the phenotype of an individual is most suited for the environment it is in
it becomes common relatively quickly by natural selection
86
what is natural selection
idea that some species are better adapted to their environment which allows them to survive and breed properly
87
what is speciation
when completely new species are formed so the two organisms can no longer produce fertile offspring
88
what is extinction
when there in no living individual of a species remaining
89
what is the theory of evolution
all of todays species have evolved from simple life forms that first started to develop over three billion years ago
90
who came up with the theory of evolution
charles darwin
91
how does natural selection work
all individuals within a species show a wide range of variation for a characteristic. This means that some individuals are better suited to the environment than other species. The individuals most suited are most likely to survive and breed successfully. These characteristics will be passed on over generations leading to evolution and the possibility of new species
92
what are the 5 reasons why species become extinct
- environment changes too quickly so species do not have time to adapt
- a new predator kills them all
- a new disease kills them all
- they cannot compete with other species for food
-a catastrophic event happens that kills them all at the same time
93
what is evolution
change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.
94
what is selective breeding
it is the process by which humans breed plants and animals for desirable characteristics
95
where might selective breeding occur
in farming for higher yields
domesticating animals
for decorative plants with unusual flowers
96
what is a disadvantage of selective breeding
reduces gene pool
97
what is a gene pool
all the different alleles for a particular gene
98
why is the gene pool reduced during selective breeding
because the desirable characteristics are selected and the alleles which create the undesirable ones slowly begin to eliminate
99
how does reducing gene pool lead to no variation
because only the desirable alleles in the organisms is left to pass down meaning most of the offspring will have the same alleles as each other.
100
what is the process of selective breeding
from stock select the organisms with desirable characteristics
breed them
then select the offspring which have the desired characteristics and breed them together
by continuing this process over generations the desirable traits get stronger and eventually all offspring will get the characteristic
101
how can selective breeding lead organisms to their extinction
by reducing genetic variation due to limiting gene pools as important traits like disease resistance may be lost making the organisms vulnerable to diseases or genetic defects making it harder for the population to survive and eventually lead to their extinction
102
what is genetic engineering
genetic engineering is a process which involves modifying the genome of an organism by introducing a gene from another organism of a different species
103
what is the process of genetic engineering
cut the desired gene of an organism from its genome using an enzyme
then insert it in a vector, usually a virus or a bacterial plasmid
then the vector with the desired gene is inserted into the organism being modified, this can only happen in the early stages of development so in a zygote or embryo
when the gene has been successfully transferred to the organism being modified, the desired gene will them be displayed
104
what are the advantages of genetic engineering
it increases yields in crops
crops can be resistant to pests and diseases
genetically modified crops are able to grow in hot, cold, dry or flooded conditions
105
what are the disadvantages of genetic engineering
reduced farmland biodiversity - gm crops can affect number of wildflowers and then numbers of insects
some people think it can harm the human health and lead to development of allergies
some people think gm genes can get into the natural environment
106
what are fossils
remains of dead organisms
107
what are the three type of fossils
gradual replacement of minerals
cast of impression
preservation of fossils
108
what is the process involved for gradual replacement of minerals
bones of the dead organism will decay very slowly so minerals will replace the bones.
109
what is the process involved in cast of imprssion
leaves or footprints are imprinted in soft ground which then hardens
110
what is the process involved in preservation of fossils
organisms is preserved in amber and there is no decaying as there is no oxygen meaning there will be no decomposers and the temperature needs to be optimum
111
why are fossil records incomplete
because geological activity destroyed many fossils
some were soft bodied so they didn't form fossils
112
