Inheritance, Variation and Evolution Flashcards
1
Q
What is all the genetic material in a cell made up of?
A
DNA
2
Q
What does DNA contain?
A
Coded information
3
Q
What does DNA determine?
A
The inherited characteristics
4
Q
Where is DNA found?
A
In the nucleus of plant and animal cells
5
Q
What normally comes in pairs?
A
Chrmosomes
6
Q
What is DNA made up of?
A
2 strands (of nucleotides) coiled together in the shape of a double helix
7
Q
What is a gene?
A
A small section of DNA found on a chromosome
8
Q
What does each gene code for?
A
A particular sequence of amino acids
9
Q
How many amino acids are there?
A
20
10
Q
Different combinations of _____ ____ are used to make different ______
A
Amino acids
Protein
11
Q
How does the DNA determine what kind of cell it is?
A
It determines what proteins the cell produces, determining what kind of cell it is
12
Q
What is a genome?
A
An entire set of genetic material in an organism
13
Q
What is the sex of someone determined by?
A
Their sex chromosomes
14
Q
How many pairs of chromosomes do humams have?
A
23
15
Q
What is the sex chromosome for males?
A
XY
16
Q
What is the sex chromosome for females?
A
XX
17
Q
What is the monomer that makes up DNA called?
A
Nucleotides
18
Q
What do nucleotides join together to form?
A
Polynulceotides
19
Q
What does a nucleotide consist of?
A
A phosphate
A sugar A base
20
Q
How many different bases are there?
A
4
21
Q
What are the different bases?
A
A, T, C, G
22
Q
What does the order of bases in a gene decide?
A
The order of amino acids
23
Q
How many bases code for an amino acid?
A
A sequence of 3 bases
24
Q
What are the base links?
A
A-T
C-G
25
What do amino acids join to make?
Proteins
26
What do parts of DNA that don't code for proteins control?
Whether or not a gene is expressed - used to make a protein
27
What happens during transcription?
The gene in the DNA is 'copied' into a molecule of RNA called mRNA
28
What does mRNA do?
It acts as a messenger between the DNA and ribosomes - carries the code between the 2
29
What happens during translocation?
The mRNA attaches to the ribosome and the ribosome reads 3 bases at a time. Carrier molecules bring the correct amino acids and they are attached to the amino acid chain
30
During translocation, what is the order of amino acids in the polypeptide determined by?
By the mRNA code
31
What happens when the protein is completed, has been coded for?
It fold into a unique shape
32
What is special about the shape of a protein?
It allows the protein to carry out a specific function
33
What are examples of proteins?
Enzymes, hormones, structural proteins
34
What is a mutation?
A change in an organism's DNA - the sequence of DNA bases in a gene
35
What happens because of mutations?
The change in genes could mean a different amino acid is coded for, meaning the sequence of amino acids that make up a protein changes. This could potentially lead to changed in the protein (from it folding incorrectly)
36
What can mutations in a non-coding gene cause?
It may alter gene expression, leading to a gene being turned on or off
37
What is insertion?
When a new base is inserted into the DNA base sequence
38
What can happen because of an insertion?
It changes the way groups of 3 bases are read, potentially changing the amino acid it codes for
They could change more than 1 amino acid as they have a knock-on effect further on the sequence
39
What is deletion?
When a random base is deleted from the DNA base sequence
40
What can happen because of a deletion?
It changes the way groups of 3 bases are read, potentially changing the amino acid it codes for
They could change more than 1 amino acid as they have a knock-on effect further on the sequence
41
What is substitution?
When a random base in the DNA sequence is changed to a different base
42
What is sexual reproduction?
Where genetic information from 2 organisms is combines to produce unique offspring which are genetically different to each parent
43
Through what process are gametes formed?
Meiosis
44
How many chromosomes does each gamete in humans contain?
23 - haploid
45
How does the egg and sperm cell form a cell with the full number of chromosomes?
They fuse together - fertilisation
46
What does having 2 parents mean to the offspring's genes?
The offspring contains a mixture of the parent's genes
47
What does a mixture of genetic variation allow in the offspirng?
Variation
48
Why is variation important?
Because it prevents a disease prom wiping out a population, gives a survival advantage, allows for evolution and adaptations
49
Why is adaptation important?
Because individuals with characteristics that make them better adapted to the environment have a better chance of survival
50
__________ _______ can be used to speed up __________ selection
Selective breeding
| Natural
51
What does natural selection allow us to do?
Produce animals with desirable characteristics
52
What are disadvantages of sexual reproduction?
It is a slow process
| You need 2 of the species
53
What are advantages of sexual reproduction?
Allows variation in offspring
| Allows for natural selection
54
How many parents are needed in asexual reproduction?
1
55
What is asexual reproduction?
Reproduction with 1 parent, resulting in offspring that are genetically identical
56
How does asexual reproduction happen?
By mitosis
57
What are the daughter cells like during mitosis?
A clone of the parent cell - same genetic information
58
Why does asexual reproduction use less energy than sexual reproduction?
Because the organisms don't have to find a mate during asexual reproduction
59
What is faster: asexual or sexual reproduction?
Asexual
60
What is produced by meiosis?
Gametes
61
Before the cell divides what happens, during meiosis?
It duplicates genetic info - 2 armed chromosomes
62
Describe meiosis:
Duplicates the genetic info
Lines up in pairs at centre of cell
During first division, pairs separated - a mix of chromosomes go into new 2 cells
During second division, chromosomes line up the centre and the arms are pulled apart
63
How many gametes are formed by meiosis?
4
64
Are gametes formed by meiosis genetically identical?
No
65
Why are gametes formed by meiosis not identical?
Because all the chromosomes get mixed up during meiosis
66
What cells go through mitosis?
Body cells
67
How many daughter cells are formed by mitosis?
2
68
How many chromosomes are there in the daughter cells in humans by mitosis?
46
69
Are daughter cells of mitosis genetically identical?
Yes - they are clones
70
When do human cells go through mitosis?
In an embryo to produce lots of new cells
71
Is cystic fibrosis dominant or recessive?
Recessive
72
Is polydactyly dominant or recessive?
Dominant
73
What can embryos be screened for before they are implantes?
Genetic disorders
74
For Embryonic Screening:
It helps stop people suffering
Treating disorders costs the government a lot of money
There are laws to prevent it from going too far
75
Against Embryonic Screening:
Implies people with disorders are 'undesirable'
Everyone will want to screen their embryos to choose their favourite
Screening is expensive
76
What causes variation?
Combining genes from 2 parents
77
What causes environmental variation?
Conditions that organisms live and grow in
78
What happens when the environment changes?
An individual becomes more suited to the new environment by mutations occurring and this change becomes common through natural selection
79
What do mutations result in?
A new phenotype being seen in species
