variation/inheritance Flashcards
1
Q
what chemical makes all genetic material in a cell
A
dna-deoxyribonucleuic acid
2
Q
what does dna contain
A
coded info to put organism together and work
3
Q
what do the contents of dna determine
A
your inherited characteristics
4
Q
how is dna found in plants and animals
A
nucleus as long pairs of chromosomes
5
Q
how is dna a polymer
A
it is made of 2 strands coiled to form a double helix
6
Q
what is a gene
A
small section of dna found on chromosomes
7
Q
what does code for mean
A
tells cell to make
8
Q
how is a specific protein made
A
gene codes for particular sequence of monomers(amino acids)
8
Q
how many amino acids are there to be used in coding but what still happens
A
20
-make up 1000s of unique proteins
9
Q
what is the role of genes
A
order to put amino acids together
10
Q
what are egs of proteins a cell can produce
A
haemoglobin or keratin
11
Q
what are egs of cells dna can make
A
rbc
skin cells
12
Q
what is the genome
A
whole genetic material in an organism
13
Q
What does understanding the human genome allow
2 facts
A
-scientists to identify genes linked to diseases
-genes linked to inherited diseases and learning abt them to develop treatment
14
Q
What does understanding the human genome allow
3rd fact
A
tracing of migration by differences of genome
15
Q
what repeating units make up dna strands
A
nucleotides
16
Q
what does each nucleotide contain
A
a sugar,base and phosphate group
17
Q
what groups form the backbone of the dna strands
A
A sugar and phosphate group
18
Q
what are the 4 bases
A
a
c
t
g
19
Q
what do the bases join to
A
1 of 4 joins to each sugar
20
Q
What is complementary base pairing
A
a pairs with t
c pairs with g
each base of a pair is on opposite strands of the helix
21
Q
what do the order of bases in a gene determine
A
order of amino acids in a proteins
22
Q
what codes for each amino acid
A
sequence of 3 bases
23
Q
What do parts of Dna that dont code for proteins do
A
switch gene on and off to show whether it is
expressed or not(to make a protein)
24
where are proteins made
in ribosomes
25
what does mRNA do
carries code from dna to ribosome
26
how is mRNA made
copying code from dna to make proteins
27
eg of proteins and functions
enzymes
hormones-carry messages around the body
27
after chain of amino acids is formed what does it do to carry out its function
folds into a unique shape
28
what is a mutation
random change in an organisms dna that may/not be inherited
29
what increases chance of mutation
radiation exposure
30
what do mutations cause in dna
change in sequence of bases in gene which forms a genetic variant and protein variant
31
some mutations are harmless
list egs of harmful mutations
enzyme active site
structural proteins(eg collagen) may lose strength
32
what can change how genes are expressed
mutation in non coding Dna
33
what are types of mutations
insertions
deletions
substitions
34
What does insertion do
adds base into dna sequence where it shouldnt be affecting amino acids they code for(can be many)
35
which mutation types have knockon effects
-deletion and insertions
36
what is sexual reproduction
genetic information from 2 parent organisms combine to produce genetically different offspring
37
what do mother and father produce in reproduction
gametes
38
what is the fusion of egg and sperm and what is the cell it makes called
fertilisation
-diploid
39
how is there variation in a fertilised egg
gametes fuse and because there are 2 parents offspring have mix of parents genes/chromosomes
40
what happens in asexual reproduction
1 parent produces genetically identical offspring by mitosis
41
what is the new cell by asexual reproduction called
clone
42
what is a clone
genetically identical copy off a parent
43
what makes the sexual reproduction of a flowering plant different to animals
their sperm is pollen
44
what organisms do asexual reproduction
bacteria
some plants/animals
45
how are gametes produced
cells dividing by meiosis
46
where does meiosis happen in humans
reproductive organs
ovaries in woman
testes in males
47
1st step of meiosis
cell duplicates genetic info (chromosomes)
which arrange themselves in pairs
48
2nd step of meiosis after chromo replicate
pairs of chromosomes line up in centre of the cell
49
3rd step of meiosis after chromosomes align
pairs are pulled apart so each cell has one copy of each(mix of fathers and mothers
cell divides
50
4th step of meiosis after chromosomes pulled apart
chromosomes realign in centre of each cell where arms are pulled apart
51
why are all the gametes from meiosis genetically different
all the chromosomes get shuffled and each gamete gets a random 23
51
what are you left with after meiosis
4 genetically different gametes with 23 chromosomes
52
what happens after gamete fusion
new diploid cell divides by mitosis to produce copies of itself
53
how are lots of cells produced in an embyro
repeated mitosis by the fertilised egg cell
54
what happens as an embyro develops
cells begin to differentiate to specialised cells that make up an organism
55
1 advantage of sexual reproduction
variation in offspring
56
2nd advantage of sexual reproduction
variation increases offspring's survival chance in a change of environment
57
3rd advantage of sexual reproduction
better adapted individuals will survive and are more likely to pass characteristic on
(natural selection)
58
how can we speed up natural selection
which is a plus of sexual reproduction
by selective breeding
59
what is selective breeding
individuals with desired characteristics bred to produce offspring with these
60
what is an example of selective breeding
increasing food production by breeding animals that produce a lot of meat
61
1 advantages of asexual reproduction
only 1 parent needed
62
2nd/3rd advantage of asexual
less energy used as organisms dont have to find a mate
faster
63
4th advantage of asexual
many identical offspring can be produced in favourable conditions
64
what is an eg of favourable condition
bacteria in human body
65
what is a con of asexual
if there is an unfavourable change in the environment that kills one organism they could all die as they are genetically identical
66
3 organisms that change between asexual/sexual depending on circumstances
fungi
malarial parasites
plants
67
malarial parasite changing reproduction conditions
malaria parasite
- sexually in mosquitos
-asexually in human host
68
fungi changing reproduction conditions
release spores which can become new fungi and reproduce asex/sex
69
what is the difference between asexual/sexual spores
asex-genetically identical to parents
sex-varied
70
what benefit do sexual spores have over asex
they are often made in response to unfavourable environmental change,so more likely to survive
71
plant changing reproduction conditions
mainly produce seeds sexually
sometimes asex-bulbs(daffodils) and runners(strawberries)
72
explain asex reproduction in runners
strawberry plants they are stems that grow on soil surface away from plant
-forms identical plant on point of runner
73
explain asex in bulbs
daffodil which grows from bulbs form new bulbs and split off growing into identical new plant
74
how many chromosome pairs are there in every human body cell
23 pairs
75
what do 22 of the chromosome pairs control in a body cell human
characteristics
76
what does the last chromosome pair control and what is the pair that forms each
-gender
-xx is female
-xy is male
77
what chromosome causes male characteristics
y
78
in making sperm/ what happens to the chromosomes
they are split by meiosis and sperm has 50% change of getting x or y
same with egg but xx
79
y chromosome is size wise
smaller than x
80
what do genetic diagrams allow us to do
find the probability of all genetic outcomes of offspring
81
what are eg of single genes that control many characteristics
mouse fur colour
red green colour blindness
82
how are most characteristics controlled
several genes interacting
83
what are alleles
different versions of the same gene
84
homozygous trait
heterozygous trait
2 same alleles for a gene
2 different alleles for a gene
85
how can an organism display a recessive trait
if 2 alleles are recessive
eg(cc)
86
how can an organism display a dominant trait
by having one or both dominant alleles
as a dominant overrules a recessive one if an organism is heterozygous
87
what is genotype
combination of alleles you have
88
what is phenotype
a persons observable characteristics
89
what is and what causes cystic fibrosis
a genetic disorder from the cell membrane
caused by a recessive allele
90
what are the effects of cystic fibrosis
body produces lots of sticky thick mucus in air passages and pancreas
91
for a child to get cystic fibrosis what must happen
parent must be carriers or affected as it is recessive
92
what is polydactyly
a non threatening genetic disorder where baby is born with extra toes/fingers
93
what type of allele is polydactyly
dominant
94
what does polydactly being a dominant allele mean
it can be inherited if just one parent carries the allele(they have it as it is dominant)
95
what is embyro screening
testing whether embyros have genetic disorders
96
1st step of embyro screening by ivf
embyros fertilised in lab and implanted in mothers womb
97
2nd step after embyro implanted in ivf
before all this cell can be removed from embyro to analyse genes
98
what does analysing genes of a cell from a fertilised ivf embyro do
help detect genetic disorders(eg cystic fibrosis)
99
apart from viewing cells of ivf embyro how can disorders be tested for
by getting dna from embyro in womb and testing for that disorder
100
what types of concerns surround embyro screening
social
economic
ethical
101
what decisions can screening from womb and embyro lead to
womb-termination of pregnancy
ivf-destroying embyros with bad alleles
102
3 arguments for embyronic screening
stops suffering
treating disorders is expensive
laws to stop it going too far
103
2 arguments against embyronic screening
-implies that people with genetic disorders are undesirable(prejudiced
-expensive
104
3rd argument against embyronic screening
may lead to everyone wanting to do it so they can choose most desirable embyro
105
what and when did Mendel do
noted how characteristics in plants were passed on generations in mid 19th century
106
when was mendels research published and what did it become
became foundation of modern genetics on 1866
107
mendels 1st observations after crossing tall and dwarf pea plants
all tall offspring
108
mendels observations after crossing offspring of 1st pea plants
3 tall 1 dwarf
109
1st conclusion mendel made about hereditary units
determine characteristics in plants
110
2nd conclusion mendel made about hereditary units
passed to offspring 1 from each parent unchanged
111
3rd and final conclusion mendel made about hereditary units
either dominant or recessive
112
why may it have taken long for people to understand mendels work
scientists of the day had no background knowledge to understand findings
113
1st progress of genetics after mendel died
in late 1800s scientists became familiar with chromosomes
114
what could scientists observe about chromosomes in late 1800s
their behaviour in cell division
115
2nd progress of genetics after mendel died
discovered close similarities between chromosomes and hereditary units
116
what did the similarity between hereditary units and chromosomes lead to
units becoming known as genes
117
in 1953 what happened
structure of dna was determined so scientists could find out how genes worked
118
apart from pea plant heigt what else did mendel look at
coulour of pea plant flowers
shape of peas
119
why do organisms from the same species look different/have diff characteristics
as there is variation within species
120
what are the 2 types of variation
genetic and environmental
121
why do offspring have similar characteristics to their parents
as they are determined by genes inherited by parents
122
where are inherited genes passed on
in gametes from which offspring develop
123
what causes genetic variation
combination of genes from 2 parents
124
what is a case where two of the same species are genetically identical
identical twins
125
3 egs of characteristics controlled only by genes in animals
eye colour
blood group
inherited disorders
126
eg of organism affected by an environmental factor
plant grown in sunlight is luscious and green
plant in darkness
tall spindly with yellow leaves
127
what are most characteristics due to
eg
mix of genetic and environmental factors
eg:max height is determined by genes but whether it grows depends on environment(eg how much food it gets)
128
what are mutations in terms of bases
change in base sequence
129
what is a + that may happen in mutations
if environment changes and new phenotype is made by mutation natural selection may occur
130
what is the theory of evolution
all todays species evolved from simple life forms that developed over 3 billion years ago
131
what did darwin know 2 things
organisms had to compete for limited resources in an ecosystem
species had wide variation
132
what did darwin conclude
organisms with most suitable characteristics would be more likely to suvive
133
what was darwins conclusion called
survival of the fittest
134
how does survival of the fittest lead to evolution
advantageous characteristics become more common and species changes/evolves
135
why wasnt darwins theory perfect 1st reason
scientific knowledge wasnt available to tell why new characteristics appeared
136
why wasnt darwins theory perfect 2nd reason
unknown how single organisms passed on beneficial adaptations to offspring
137
why may a species die out
it cant evolve fast enough
138
without evolution we wouldnt have
the variety of life we have on earth today
139
what is speciation
development of a new species
140
how does speciation occur
over long time organisms phenotype chnages due to natural selection a new species is formed
141
when does speciation happen
when same species cant interbreed to produce fertile offspring(reproductively isolated)
142
what is extinction
when no individuals of a species remain
143
3 reasons a species may become extinct
environment changes too fast(eg habitat destroyed
new predator kills them(eg human hunting)
new disease
144
2 more reasons a species may become extinct
cant compete with new species for food
killed in catastrophic event(eg volcano/asteroid)
145
why was darwins theory controversial 1 reason
was the first plausible explanation for life existing without God
146
why was darwins theory controversial 2 reason
he couldnt explain how useful characteristics appeared/got passed on
147
last reason why was darwins theory controversial
not enough evidence to convince other scientists
148
what was lamarcks theory
changes an organism acquires develops during lifetime and is passed onto offspring
149
eg of lamarcks theory
giraffe stretching neck to reach high trees
150
why may scientists have different hypotheses for similar observations
have diff beliefs
influenced by diff people
151
how can one prove a hypothesis is right
to find evidence to support or disprove others
152
why was lamarcks theory disproved
experiments didnt support hypothesis
153
eg of why lamarcks theory disproved
dying hamster fur pink still produces normal fur offspring as new trait isnt passed on
154
what supported darwins theory
discovery of genetics-showed how traits can be passed on
fossil record
155
selective breeding
humans artificially selecting plants or animals that breed so certain traits remain.
156
eg of useful features of selective breeding
disease resistant crops
animals that produce more milk/meat
dogs with good/gentle temperament
157
process of selective breeding 1st 2 steps
from stock choose organisms with desired trait
breed together
158
last 2 steps of selective breeding
select best offspring and breed
repeat over several geberations and all offspring will have characteristic
159
selective breeding in agriculture
improves yields-eg meat yield
farmer could breed best cows and bulls and would get cows with high meat yield
160
