section 7 - reproduction and inheritance Flashcards
1
Q
what is a gene
A
short section of DNA that codes for a particular protein
2
Q
how many chromosomes in a human body cell
A
diploid - 46
3
Q
what are different versions of the same gene
A
alleles - blue or brown eyes
4
Q
what are two strands of DNA
A
double helix
5
Q
what are the two strands held together by
A
chemicals called bases
6
Q
what are the 4 bases
A
adenine, cytosine, guanine, thymine
7
Q
which base is A paired with
A
T
8
Q
which base is C paired with
A
G
9
Q
what does DNA control
A
production of proteins - protein synthesis in a cell
10
Q
what does each protein have
A
a particular number and order of amino acids
11
Q
what decides the order of amino acids in a protein
A
the order of bases
12
Q
how many bases in a codon
A
3
13
Q
how do genes code for a particular protein
A
contain different sequences of bases
14
Q
DNA also contains non-coding regions means…
A
they dont code for any amino acids
15
Q
what cell are proteins made in
A
ribosomes in the cytoplasm
16
Q
why cant DNA move out of the nucleus
A
its to big
17
Q
what is the molecule that get the information from the nucleus to the ribosome
A
mRNA
18
Q
what is mRNA made up of
A
sequence of bases that is shorter and a single strand
19
Q
what is the enzyme that joins together the base sequence to make mRNA
A
RNA polymerase
20
Q
what are the steps of transcription
A
- RNA polymerase brings a region of non-coining DNA in front of a gene
- the two DNA strands unzip and the RNA polymerase moves along one of the strands of DNA
- it uses the coding DNA in the gene as a template to make mRNA. base painting between DNA and RNA ensures that mRNA is complementary to the gene.
- once made the mRNA molecule moves out of the nucleus and joins with a ribosome in the cytoplasm
21
Q
what does mRNA use instead of T
A
U - uracil that pairs with A
22
Q
what are the steps of translation
A
- amino acids are brought to the ribosome by another RNA molecule called tRNA
- the order in which the amino acids are brought to the ribosome matches the order of the codons in mRNA.
- part of the tRNA structure is called an anticodon - it is complementary to the codon for the amino acid. the pairing of the codon and anticodon make sure that the amino acids are brought to the ribosome in the correct order.
- the amino acids are joined together by the ribosome. this makes a protein.
23
Q
what cell decision is asexual reproduction
A
mitosis - genetically identical and contain exactly same genetic information
24
Q
what is the definition of asexual reprodiction
A
involves one parent. the offspring have identical genes to the parent - so there is no variation between parent and offspring
25
definition of mitosis
when a cell reproduces itself by splitting to form two cells with identical sets of chromosomes
26
what is the 1st stage of mitosis
interphase - The cell spends most of its life in this phase. The DNA in chromosomes copies itself ready for mitosis.
27
what is the 2nd stage of mitosis
Prophase- The DNA in chromosomes and their copies condenses to become more visible. The membrane around the nucleus disappears.
28
what's the 3rd stage of mitosis
Metaphase Chromosomes and their copies line up in the middle of the cell.
29
what the 4th stage of mitosis
Anaphase Chromosomes and their copies are pulled to different ends of the cell by cell fibres
30
what is the 5th stage of mitosis
Telophase New membranes form around the chromosomes at each end of the cell.
31
what is Cytokinesis
The cell membrane pinches in and eventually divides into two daughter cells.
32
what is mitosis used for
growth and repair
33
how many daughter cells in mitosis and how many chromosomes
2 genetically identical diploid cells with 46 chromosomes
34
what are gametes
sperm and egg cells
35
how many chromosomes in gametes
haploid 23
36
what does the fuse of gametes cause
zygote with full set of chromosomes
37
definition of sexual reproduction
involves the fusion of male and female gametes because there are to parents, the offspring contain a mixture of their parents genes
38
where does meiosis happen
gametes
39
definition of meiosis
produces 4 haploid cells whose chromosomes are not identical
40
what happens in division 1 of meiosis
1. DNA duplicates and one arm is the exact copy of other arm
2. chromosomes line up in pairs at centre. one chromosomes in each pair comes from mother and one from father.
3. the pairs are pulled apart so new cell has copy of Rach chromosome. some are mothers and some are fathers go into each new cell
4. each new cell with have a mixture of mothers and fathers chromosomes which cause genetic variation
41
what happens in division 2 of meiosis
1. the chromosomes line up again in the centre of the cell. the arms of the chromosomes are pulled apart
2. 4 haploid gametes. each gamete only has a single set of chromosomes and they are genetically different
42
4 differences between mitosis and meiosis
mitosis produces 46 chromosomes - diploid. meiosis produced 23 chromosomes - haploid
mitosis produces 2 daughter cells, meiosis produces 4.
mitosis is for growth and repair and asexual reproduction and meiosis is for gametes only.
mitosis daughter cells are genetically identical. meiosis are all genetically different.
43
what is the male part of the plant and what does it contain
stamen - filament and anther
44
what is the function of the anther
contains pollen grains - produce male gametes
45
what is the function of the filament
supports the anther
46
what is the famale part of the plant
carpel - ovary, style and stigma
47
what is the function of the stigma
pollen grains attach to
48
what is the function of the style
supports the stigma
49
what is the function of the ovary
contains female gametes inside ovules
50
what is pollination
transfer of pollen from an anther to a stigma so male gametes can fertilise the female gametes in sexual reproduction
51
what is cross-pollination
sexual reproduction where pollen is transferred from the anther of one plant to the stigma of another
52
what helps a plant pollinate
insects , wind
53
how are plants adapted for insect pollination
1. bright coloured petals to attract insects
2. scented to attract
3. big, sticky pollen grains to stick to insects as they go from plant to plant
4. the stigma is also sticky so that any pollen will stick
54
how are plants adapted for wind pollination
1. small dull petals
2. a lot of small and light pollen grains to be carried by the wind
3. long filament that hang the anthers outside the flower to get blown by the wind
55
how are plants adapted for wind pollination
1. small dull petals
2. a lot of small and light pollen grains to be carried by the wind
3. long filament that hang the anthers outside the flower to get blown by the wind
4. a large feathery stigma to catch pollen that hangs outside flower to
56
what is fertilisation
the fusion of gametes
57
what are the steps of plant fertilisation
1. After pollen has landed on the stigma, it grows a pollen tube down through the style to the ovary.
2. The nucleus of the pollen grain travels down the pollen tube and fertilises the nucleus in the ovule.
3. The fertilised ovule develops into a seed. The seed contains the plant embryo, which contains genetic material from both parents. The ovary develops into the fruit.
58
what are the conditions for a seed to germinate
water - to activate the enzymes that break down the food reserves in the heat
oxygen - for respiration
suitable temp - for enzymes to work
59
how do germinating seeds get energy
from food stores
60
what conditions would each of 4 tubes have in to investigate the conditions needed for germination
tube 1: water, oxygen, room temperature (control).
tube 2: no water, oxygen, room temperature
tube 3: water, oxygen, low temperature
tube 4: water, no oxygen, room temperature
61
what are the observations from the conditions needed for germination
only see germination in tube 1 because all conditions are needed for germination are present
62
what is a natural method for plants to clone
1. runners - fast growing stems
2. the runner take root at various points
3. the new plants are clones of the parent plant
63
what is an artificial method to clone plants
taking cuttings
cuttings kept in moist conditions until ready to plant. cloned plant
64
what is the prostate gland for?
produce liquid thats added to sperm to make semen
65
what is the urethra for
carries sperm or urine out of the body
66
what is the testis for
where sperm is made
67
what is the vas deferens
carries sperm from testis towards urethra
68
what is the erectile tissue for
swells up when filled with blood to make penis errect
69
what is the endometrium
lining of the uterus with good blood supply for implantation of an embryo
70
what are female secondary characteristics
1. extra hair on underarms or pubic area
2. hips widen
3. development of breasts
4. ovum release and start of periods
71
what are male secondary characteristics
1. extra hair on face and body
2. muscles start to develop
3. penis and testicles to enlarge
4. sperm production
5. deepening voice
72
what does FSH stimulate
egg to mature in follicle, stimulates ovaries to produce oestrogen and oestrogen inhibits release of FSH
73
what does oestrogen stimulate
lining of uterus to grow, stimulates release of LH
74
what does LH stimulate
stimulates release of egg at day 14
75
what does progesterone stimulate
maintains the lining of the uterus. the level of progesterone falls, the lining breaks down. inhibits the release of LH and FSH.
76
what is the placenta for?
blood of embryo and mother to get very close to allow the exchange of food, oxygen and waste
77
what is the amniotic fluid for?
protects the embryo against knocks and bumps
78
what is your genotype
the alleles that you have
79
what is the phenotype
the characteristics the alleles produce
80
what is homozygous
two of the same alleles
81
what is heterozygous
two different alleles
82
what are coo dominant alleles
both characterists from both alleles like blood group AB
83
what are male chromosomes
xy
84
what are female chromosomes
xx
85
what is variation caused by
genetic and environmental factors
86
what is a genetic factor
eye colour, hair colour
87
what is an environmental factor
poor diet can stunt growth
88
4 things plants are strongly affected by
1. sunlight
2. moisture level
3. temperature
4. mineral content in soil
89
what is the theory of evolution
life began as simple organisms from which more complex organisms evolved
90
what is natural selection
1. genetic variation in characterists
2. most suitable characterists for that environment would have a better chance of survival
3. breed and reproduce
4. pass on alleles
91
how do mutations produce genetic variant
change the sequence of the DNA bases in a gene
92
how do mutations increase variation
lead to different phenotype
93
what are 2 reasons for the chance of mutation to be increased from exposure
- ionising radiation
- chemicals called mutagens like in tabacoo
94
what is a superbug
bacteria that are resistant to most known antibiotics and are becoming more common
