Reproduction and Inheritance Flashcards
(75 cards)
1
Q
where are chromosomes found and what are they?
A
-found in the nucleus
-they are long length of DNA coiled up
2
Q
what is a gene?
A
a short section of DNA
3
Q
what does diploid mean?
A
-means a cell has two hippies of each chromosome, arranged in pairs
4
Q
how many chromosomes does a human body cell have?
A
46
5
Q
what does haploid mean and what cells are haploid?
A
-they have half the normal number of chromosomes
-gametes
6
Q
what does all of an organism’s DNA make up?
A
its genome
7
Q
what does a gene do?
A
codes for a particular protein
8
Q
what does a protein control and determine?
A
-controls most processes in the body
-determines inherited characteristics
9
Q
what is an allele?
A
different versions of the same gene which give different characteristics
10
Q
what shape is DNA?
A
a double helix
(two strands coiled together)
11
Q
what are the 2 DNA strands held together by?
A
chemicals called bases
12
Q
what are the 4 bases called?
A
-adenine
-cytosine
-guanine
-thymine
13
Q
what are the complementary base-pairings?
A
-A+T
-C+G
14
Q
what are proteins made up of?
A
-chains of amino acids
15
Q
when the amino acids fold up what happens?
A
forms a specific shape
16
Q
why is the shape important?
A
-it is designed for a function
17
Q
what decides the order of amino acids in a protein?
A
the order of bases in the gene
18
Q
each amino acid is coded by a sequence of three bases in the gene. what is this called?
A
a codon
19
Q
how many possible codons are there?
A
64
20
Q
how many amino acids are there?
A
20
21
Q
how do some codons code for the same amino acids?
A
there are only 20 amino acids and 64 combinations of bases
22
Q
what is a non-coding region?
A
means they don’t code for any amino acids but are still involved in protein synthesis
23
Q
where are proteins made?
A
in the ribosomes
24
Q
why can’t DNA move out of the nucleus?
A
its too big
25
how does genetic information get out of the nucleus?
using mRNA
26
what is mRNA made up of?
and what does it use instead of thymine?
-made up of a sequence of bases, but it's shorter and only a single strand
-uracil
27
describe the 4 stages of transcription?
1. RNA polymerase bind to a non-coding region of DNA in front of a gene
2.the two DNA strands unzip and the RNA polymerase moves along one of the strands of DNA
3.it uses the coding DNA in the gene as a template to make the mRNA
4.once made the mRNA molecule moves out the nucleus and joins with a ribsome
28
describe the 4 stages of translation
1. amino acids are brought to the ribosome by tRNA
2.the order in which the amino acids are brought to the ribosome matches the order of codons in mRNA
3.the pairing of the codon and anticodon make sure that the amnio acids are brought in the ribosome in the right order
3.the amino acids are jointed together by the ribosome to make a protein
29
what is the anticodon?
complementary to the code for the amino acid
30
what type of cell division does asexual reproduction involve?
mitosis
31
give 2 characteristics of a cell which has been produced by mitosis?
-the new cells are genetically identical to each other and the mother cell
-hey both contain the exact same genetic information
32
state an organism which reproduces asexually?
-bacteria
-some plants
33
define asexual reproduction
asexual reproduction involves on,y one parent. the offspring have identical genes to the parent so there is no variation between the parent and offspring
34
define mitosis
mitosis is when a cell reproduces itself by splitting to form two cells with identical sets of chromosomes
35
in a cell that's not dividing how is the DNA spread out?
evenly spread out in long strips
36
describe the 4 steps of mitosis
1.the cell duplicates its DNA and forms X-shaped chromosomes (each arm duplicates the other)
2.the chromosomes then line up at the centre of the cell and cell fibres pull them apart. (the two arms of each chromosome go on opposite sides of the cell)
3.membranes form around each of the sets of chromosomes. these become the nuclei of the two new cells
4.then the cytoplasm divides and the two new cells are formed
37
what use other than reproduction does mitosis serve?
growth and repair and cloning
38
define sexual reproduction
sexual reproduction involves the fusion of male and female gametes, because there are 2 parents the offspring contain mixture of their parents genes and are genetically different
39
in sexual reproduction what type of cell is made and what are they called?
-gametes
-sperm and egg
40
what type of cell are gametes?
haploid
41
how does a zygote become an embryo?
undergoes cell division by mitosis
42
why does sexual reproduction produce genetic variation in the offspring?
random fertilisation of gametes
43
define meiosis
meiosis produced four haploid cells whose chromosomes comes are not identical
44
describe the 1st division of meiosis (4)
1.the cell duplicates its DNA and forms X-shaped chromosomes (each arm duplicates the other)
2.the chromosomes line up in pairs in the centre of the cell. once chromosome in each pair comes from the father and one from its father
3.the pairs are pulled apart so each new cell only has one copy of each chromosome. there is some of the fathers and some of the moths chromosomes in each cell
4.each cell will have a mixture of the mothers and fathers chromosomes. this creates genetic variation
45
describe the 2nd division of meiosis (2)
1.the chromosomes line up again in the centre of the cell and the arms of the chromosomes are pulled apart
2.you get 4 haploid gametes. each gamete only had a single set of chromosomes, the gametes are genetically different
46
what is the male reproductive part of the plant?
the stamen
47
what is the female reproductive part of the plant?
the carpel
48
what does the stamen consist of? (2)
-the anther
-the filament
49
what does the carpel consist of?
-ovary
-style
-stigma
50
what does the anther contain- what does it do?
-the anther contains pollen grains
-these produce the male gametes (sperm)
51
what is the filament?
the stalk that supports the anther
52
what is the stigma? + function (2)
-the sticky end bit that the pollen grains attach to
53
what is the style? + function (2)
-they style is the rod-like section that supports the stigma
54
what does the ovary contain?
-the female gametes (eggs) inside ovules
55
define pollination
the transfer of pollen from an anther to a stigma, so that the male gametes can fertilise the female gametes in sexual reproduction
56
define cross-pollination
a type of sexual reproduction where pollen is transferred from the anther of one plant to the stigma of another
57
what do plants that cross-pollenate rely on? (2)
-things like insects or the wind to pollinate them
58
state at least 3/4 ways plant have adapted for insect pollination?
1.brightly coloured petals to attract insects
2. scented flowers and nectaries
3.make big, sticky pollen grains to stick to insects
4.stigma is also sticky
59
what are nectaries?
glands which secret nectar
60
state 4/5 ways plants have adapted for wind pollination
1.small, dull petals(don't need to attract)
2.no nectaries or strong scents
3.a lot of small and light pollen grains to be carried by the wind
4.long filament
5.large feathery stigma
61
why do wind pollinated flowers need a long filament?
long so it can hang outside the flower and lots of pollen can be blown away by the wind
62
why do wind pollinated flowers need a large feathery stigma?
to catch pollen as it's carried past by the wind. the stigma often also hangs outside the flower
63
how does the male gamete travel to the female gamete in a plant? (4)
-once the pollen grain lands on the stigma a pollen tube grows put of the pollen grain and down through the style to the ovary and into the ovule
-then the male gamete travels down the pollen tube to fuse with the female gamete
64
how does the gametes become fertilised? (plant)
-fertilisation happens when the two nuclei fuse together to make a zygote which divides via mitosis to form an embryo
65
what happens after fertilisation? (plant)
-each fertilised female gamete forms a seed
-the ovary develops into a fruit around the seed
66
what is germination?
when seeds start to grow
67
why will seeds lie dormant?
if the conditions around then aren't right
68
what 3 conditions do plants need to be correct for germination?
-water
-oxygen
-temperature
69
why does the seed need water for germination?
to activate the exams that break down the food reserved in the seed
70
why does the seed need oxygen for germination?
for respiration which transfers the energy from food for growth
71
why does the seed need a suitable temperature for germination?
for the enzymes inside the seed to work (optimum temperature)
72
what are the 4 stages of germination?
1.the seed takes in water and starts to grow using its store of energy
2.the first root starts to grown down into the soil
3.the shoot grows up
4.finally, extra roots grow and the first green leaves appear
73
how does the seed make/use energy? (3)
-a developed seed contains and embryo and a store of food reserves, wrapped in a hard shell
-when the seed starts to germinate, it gets glucose for respiration from its own food store
-this transfers energy for the leaf to grow
74
after the plant grows its first green leaves how does it make energy?
it can make its own energy from photo
75
