Inheritance Flashcards
1
Q
What does DNA stand for?
A
Deoxyribonucleic acid
2
Q
What is DNA
A
- a polymer made up of two strands
3
Q
what is a polymer made up of?
A
lots of similar units stuck together
4
Q
Where is DNA contained?
A
-chromosomes
5
Q
What is a gene
A
- a small section of DNA on a chromosome that codes for a specific protein
6
Q
What does each gene code for?
A
-a particular sequence of amino acids to make a specific protein.
7
Q
What is the genome of an organism?
A
->the entire genetic material of that organism
8
Q
How could understanding the human genome help science?
A
->allows scientists to search for genes linked to different types of disease
->understanding and treatment of inherited disorders
->can be used in tracing human migration patterns from the past
9
Q
How much chromosomes do each of our cells have in it?
A
-46
10
Q
How many different pairs of chromosomes are there in a human cell?
A
-23
11
Q
what sex chromosomes do females have?
A
- XX
12
Q
what sex chromosomes do males have?
A
- XY
13
Q
How many types of amino acids are there?
A
20 types
14
Q
what does DNA determine?
A
-which cell the protein produces which determines what type of cell it will be
15
Q
what is the structure of DNA
A
-a double helix
16
Q
where in a cell are chromosomes located?
A
nucleus
17
Q
what are sex chromosomes?
A
-the 23rd pair of chromosomes
-they determine whether an individual is male or female
18
Q
what do genes we inherit determine?
A
-the characteristics we develop
19
Q
what are alleles
A
-different versions of a particular gene
20
Q
what are most characteristics controlled by?
A
-many genes acting together
21
Q
how many alleles of each gene does an individual have?
A
-2
22
Q
what does it mean to be ‘homozygous’ for a particular gene?
A
-Both alleles of that gene are identical
23
Q
What does it mean to be ‘heterozygous’ for a particular gene?
A
-the two alleles of that gene are different
24
Q
what is a dominant allele?
A
-the one which is always expressed even if there is only one copy of that allele
25
what is a recessive allele?
-an allele that is only expressed if there are two copies of it
26
what is genotype?
-the two alleles present for a particular gene
27
what does phenotype mean?
-the characteristics an organism has as a result of their genotype and environment
28
What are most characteristics determined by?
-the combination of multiple genes and the environment.
29
is DNA a monomer or a polymer?
-polymer
30
What are the monomers that combine to form DNA?
-Nucleotides
31
What are the names of the 4 bases that make DNA?
-Adenine (A)
-Thymine (T)
-Guanine (G)
-Cytosine (C)
32
What is complementary base pairing?
-the idea DNA bases always pair up in a similar way.
33
Which base will adenine (A) always pair with?
-Thymine (T)
34
Which base will guanine (G) always pair with?
-Cytosine (C)
35
How many bases are required to code for an amino acid?
-3 bases for an amino
36
What do we call a set of 3 bases, which code for an amino acid?
-A 'triplet' or 'codon'
37
Give 3 uses of proteins
-enzymes-
-hormones-
-structural proteins
38
describe the structure of a nucleotide
-pentagon is the sugar molecule
-the circle is the phosphate
-the rectangle is the base
39
What never changes in DNA?
-the phosphate and sugar molecule
40
how many nucleotides does DNA contain?
-4 different nucleotides
41
What does it mean for the DNA strands to be complementary?
-the same bases always pair on the opposite strands
42
What is protein synthesis?
-The formation of a protein from DNA
43
What does it mean for a gene to have been expressed?
-it is coded to make a protein
44
What does the specific order of amino acids determine?
-the specific order of amino acids determines the shape of the protein
-the shape of the protein determines its function
45
what is the order of amino acids in a protein determined by?
-the sequences of bases in the gene for that protein
46
How many stages does protein synthesis consist of ?
-two
47
Where does the first stage of protein synthesis take place in?
-nucleus
48
Where does the second stage of protein synthesis take place?
-cytoplasm
49
Describe the first stage of protein synthesis.
-this stage is called transcription
-the base sequence of the gene is copied into a complementary template molecule
-mRNA is a single-stranded molecule that passes out of the nucleus and into the cytoplasm
50
what does mRNA short for?
-complementary template molecule
51
Describe the second stage of protein synthesis
-this stage is called translation
-the mRNA molecule attaches to a ribosome.
-amino acids are now brought to the ribosome on carrier molecules
-the ribosome now reads the triplet of bases on the mRNA and uses this to join together the correct amino acids in the correct order
52
what is tRNA short for
-carrier molecules
53
What happens when the protein chain is complete?
-it now folds into its unique shape
54
what is a mutation?
-a change in the base sequence of DNA
55
What determines the amino acid sequence of a protein?
-the base sequence of a gene
56
what happens to a protein once it is formed ?
-it folds into a unique shape
57
How does the shape of a protein relate to its function?
-Th shape determines the protein's function
58
What can happen when a single base in a gene changes?
-It may not change the amino acid sequence.
59
Why might a mutation not affect protein function?
-Different base triplets can code for the same amino acid
60
What can a mutation that changes an amino acid do?
-it can alter the shape of protein
61
What might happen if the active site of an enzyme changes shape due to a mutation?
-it can no longer bind to the substrate
62
What effect can a mutation in a structural protein like collagen have?
-it may lose its strength
63
What do chromosomes contain besides coding DNA?
non-coding DNA
64
Which things increase the risk of mutations occuring?
Carcinogens- chemicals that can cause cancer.
Certain types of radiation (such as x-rays and gamma rays)
65
How do risk factors affect mutations?
-they increase the chance of mutations occurring
66
Are mutations more likely to occur in coding or non-coding DNA ?
-non-coding DNA
67
What is non-coding DNA ?
-DNA that does no code for proteins
-has a role in switching genes on and off so mutations in these areas of DNA may affect how genes are expressed
68
What happens when a gene is turned on when it should be turned off?
-the cell would produce a protein it is not meant to have at that mean
-this could have a significant effect on a cell e.g uncontrolled mitosis leading to cancer
69
What do 22 of the chromosome pairs contain ?
-the genes which determine inherited characteristics only.
70
What is cystic fibrosis?
-a inherited disorder of cell membranes
-causes sticky mucus to build up in lungs + digestive system
71
What is cystic fibrosis controlled by?
- a single gene that has two alleles
72
what is a person has one normal membrane function allele and one defective allele ?
-they do not have cystic fibrosis, we say they are a carrier of the cystic fibrosis allele
73
Key reminder for punnet squares
-they are just probabilities
74
what do people with polydactyly have?
-extra fingers or toes
75
What is polydactyly caused by?
-a dominant allele
76
Can you be a carrier of a dominant allele?
No because you will have the characteristics as even one copy of a dominant allele is expressed
77
What is a solution for inherited disorders?
-embryo screening
-in embryo screening , embryos are tested to see if they have alleles for inherited disorders
-embryos which do not have the defective alleles are implanted into the woman which develop into healthy offspring
78
What are issues for embryo screening?
-expensive
-unethical as only a small number of embryos are implanted. This means some healthy embryos are destroyed.
-in the future we may be able to screen embryos to produce offspring with desirable features which people find unethical
79
Is cystic fibrosis a dominant or recessive condition?
-recessive
80
What does it mean for an individual to be a carrier of cystic fibrosis?
-they are heterozygous and only have one cystic fibrosis allele
-they can pass it off to their offspring but do not have the condition themselves
81
What is a advantage of embryo screening?
-can reduce suffering by stopping children being born with genetic disorders
82
What is a gamete?
-a gamete is a sex cell such as a sperm cell or egg cell
83
What does the term 'haploid' mean
-a cell that only has half of the normal amount of genetic material
84
How many chromosomes do gametes have?
-23
85
Where in the body does meiosis take place?
-sex organs such as the testes in males and the ovaries in females
86
As a result of meiosis how many cells are produced?
-4
87
Are the cells produced by meiosis genetically identical or unique
-genetically unique
88
what is sexual reproduction?
-the fusion of gametes to produce fertile offspring.
89
-During sexual reproduction in animals, which two gametes fuse together?
-Sperm cell and egg cell
90
During sexual reproduction in plants which two gametes fuse together
-Pollen and egg cell
91
What is variation?
-the differences of characteristics of individuals in a population
92
What are the three main causes of variation?
-Genetic variation which is the alleles that individuals have inherited.
-The environment each individual is exposed to.
-a combination of genes and the environment
93
What are two examples of genetic variation?
-hair colour and eye colour
94
What is a example of variation caused by the environment?
-language in humans
95
What is a example of variation caused by a combination of genetics and the environment?
-height as alleles and diet can contribute to height.
96
why is is there a massive amount of genetic variation in any population of a species?
-all of this genetic variation is due to mutations
97
Do most mutations have a effect on the phenotype
-No however some mutations can influence the phenotype
- a small number of mutations determine the phenotype
98
How often can mutation lead to a new phenotype?
-very rarely
99
When can a new phenotype be beneficial?
-if the environment changes which can lead to a rapid change in the species.
100
Explain how a mutation leads to a non functional enzyme
-change in order of bases of DNA
-change in order of amino acids
-change to structure of protein
-changes shape of active site
-substrate is no longer complementary, shall not bind.
101
what happens in mitosis?
-one cell is copied into two identical cells
102
is a sperm cell haploid or diploid?
-haploid as it only has half the number of chromosomes (23)
103
What does fertilisation mean?
-the fusion of male and female gametes
104
What is asexual reproduction?
-the production of genetically identical offspring by a single parent
105
why is there variation in offspring produced by sexual reproduction?
-there is mixing of genetic information
106
asexual reproduction
-involves one parent and no fusion of gametes.
-there is no mixing of genetic information
-this leads to genetically identical offspring
-only mitosis is involved
107
what are the advantages of sexual reproduction?
-produces variation in the offspring
-if environment changes variation gives a survival advantage by natural selection
-natural selection can be speeded up by humans in selective breeding to increase food production
108
What are the advantages of asexual reproduction?
-only one parent needed
-more time and energy efficient as there is no need to find mate
-faster than sexual reproduction
-many identical offspring are produced when conditions are favourable.
109
When do malarial parasites use asexual and sexual reproduction
-malarial parasites reproduce asexually in the human host, but sexually in the mosquito.
110
When do fungi reproduce sexually or asexually?
-many fungi reproduce asexually by spores but also reproduce sexually to give variation
111
When do plants reproduce sexually or asexually?
-many plants produce seeds sexually,but also reproduce asexually by runners such as strawberry plants, or bulb division such as daffodils
112
how are gametes produced?
-by meiosis
113
how meiosis affect the number of chromosomes in a gamete?
-meiosis halves the number of chromosomes while fertilisation restores the full number of chromosomes
114
what happens when a cell divides to form a gamete?
-copies of the genetic information are made
-the cell divides twice to form four gametes, each with a single set of chromosomes.
-all gametes are genetically different from each other.
