Topic 3 - Genetics Flashcards
1
Q
Meiosis
A
A type of cell division that doesnt produce identical cells
2
Q
Asexual reproduction mainly uses
A
Mitosis
3
Q
Sexual reprodction mainly uses
A
Meiosis
4
Q
Asexual reproduction advantages
A
Produce a lot of offspring quickly
Only one parent is needed
5
Q
Asexual reproduction disadvantages
A
No genetic variation, therefore no adaptation to environment
Can spread disease due to this
6
Q
Sexual reproduction advantages
A
Genetic variation
Leading to natural selection and evolution
7
Q
Sexual reproduction disadvantages
A
More time and energy needed
Two parents are needed
8
Q
How many daughter cells does meiosis produce
A
4
9
Q
DNA strands are made up of
A
repeating units called nucleotides
10
Q
DNA strands are
A
Polymers
11
Q
A nucleotide consists of
A
Sugar and phospate groups that make the backbone fo a strand, and a base.
12
Q
The sugar and phosphate in the nucleotide
A
Alternate
13
Q
The sugar is joined with 1 of 4
A
Bases
14
Q
What are the 4 bases
A
A- adenine
T - Thymine
C - Cytosine
G - Guanine
15
Q
A base
A
Adenine
16
Q
T base
A
Thymine
17
Q
C base
A
Cytosine
18
Q
G base
A
Guanine
19
Q
A DNA molecule has a coil of
A
2 strands in a double helix
20
Q
Bases that link together
A
A - T
C - G
21
Q
The linking of bases is called
A
Complementary base pairing
22
Q
The base pairs are joined by
A
Weak hydrogen bonds
23
Q
Chromosomes
A
Long coiled up molecules of DNA
24
Q
A gene is
A
A section of DNA on a chromosome that codes for a particular protein
25
The genome
All of an organisms DNA
26
What are the steps of extracting DNA from strawberries
1) Mash them and put in a beaker of a detergent and salt solution. Mix
The salt makes the DNA stick together
The detergent breaks down the cell membranes to release DNA.
2)Filter the mixture to get the froth and large pieces of cell out.
3)Add ice-cold alcohol
4)The DNA will appear as a stringy white precipitate as its not suluble in cold alcohol.
27
Proteins are made by
Reading the code in DNA
28
Each different protein has its own
Number and order of amino acids
29
Proteins are all different shapes because
The amino acids fold up in different ways
30
Each amino acid is coded for by a sequence of
3 bases
31
A sequence of 3 bases is called
A base triplet
32
the order of amino acids is the same as the order of
Base triplets in DNA.
33
Two stages protein synthesis
Transcription, translation
34
The cell component that synthesises proteins
Ribosomes
35
What is RNA polymerase and how does it work
An enzyme involved in joining together RNA nucleotides to make mRNA
36
What is mRNA and how does it work
It is a polymer of nucleotides, but shorter than DNA and only a single strand. It uses U(Uracil) instead o T(thymine) as a base
37
Explain the process of transcription
RNA polymerase binds to a region of non-coding DNA in front of a gene.
The two strands of DNA and the RNA polymerase moves along one strand.
It uses coding DNA in the gene as a template to make mRNA. Base pairing between the DNA and RNA ensures complementary mRNA to the gene.
Once made, the mRNA moves out of the nucleus to a ribosome
38
Explain the process of translation
Amino aicds are brought to the ribosome by another RNA molecule called transfer RNA(tRNA)
The order of amino acids brought is the same as the base triplets in the mRNA
The tRNA has anticodons which are complementary to the codon for the amino acids.
The amino acids are joined together by the ribosome to make a polypeptide(protein).
39
Mutations in the non-coding DNA can lead to
RNA polymerase bonding differently, so affecting the amount of protein produced. This ca nthe naffect an organisms phenotype.
40
Gregor mendels experiment:
Crossed a tall and dwarf plant, got all tall plants.
Crossed two of these tall plants and got 3:1 ratio of tall to small.
41
Gregor mendels experiments showed
There are dominant or recessive alleles(hereditary units)
Offspring gets one unit from each parent
42
Why did people not understand inheritance befroe mendel
They didnt understand genes, DNA and chromosomes
43
How dominant and recessive alleles interact using X and x
X - Dominant
x - Recessive
XX - Dominant trait
Xx - Dominant trait
xX - Dominant trait
xx - Recessive trait
44
What is an allele
Different versions of the same gene. There are two versions of every gene in the body, one stored in each chromosome in a pair.
45
Homozygous meaning
An organism has two alleles for a particular gene that are the same
46
Heterozygous meaning
An organism has two different alleles for a particular gene
47
What is the genotype
The combination of alleles alleles that an individual has
48
What is a phenotype
The characteristics that a person has caused by the genotype
49
What is a gamete
A reproductive cell. Sperm for males and ova for women
50
What is a zygote
A fertilised egg cell created by two gametes.
51
What is monohybrid inheritance
When two genotypes cross and can only possibly give one characteristic
52
Monohybrid inheritance can be shown in 3 ways:
Genetic diagrams
Punnet squares
Family pedigrees
53
Genetic diagram description
Two genotypes are mixed. Each genotype is seperated into their alleles, then the alleles are combined to make 4 new possibloe genotypes.
54
Punnnet squares description
2 genotypes are put onto a graph, the nmixed to find the 4 new genotypes
55
Family pedigrees description
A family tree of genetic disorders, that shows if each family memebr is unaffected, a carrier, or affected.
56
Genetic diagrams can also show
How sex is determined in babies
57
The two possible pairs of chromosomes that determine sex
XY - male
XX - female
58
When one XX and one XY genotype are plugged in to a genetic diagram the result is
2 XX, 2 XY. There is always a 50/50 chance of being male or female
59
A characterisitc is sex-linked if
If the allele that codes for it is on a sex chromosome(X or Y)
60
Most genes on the sex chromosomes are located on the ..... because
X chromosome because its bigger
61
Men or more likely to show sex-linked recessive characteristics than women because
They only have one X chromosome, which has most of the sex-linked alleles. Therefore if they have a recessive allele for a charcteristic they will still have it
62
Sex-linked genetic disorders are
Disorders caused by faulty alleles on sex chromosomes
63
For genetic diagrams showing sex-linked disorders
Both the chromosome and the allele need to be included.. eg X^NX^n for a female or X^NY for males
64
Most phenotypic features are the result of
Multiple genes rather than a single gene
65
Blood group inheritance is based on
3 alleles rather than 2
66
The 4 possible blood types are
O, A, B, AB
67
The gene for blood type in humans has the three alleles:
I^O, I^A, I^B
68
The alleles IA and IB in blood groups are..... which means
They are codominant which means if an individual has both of them they will have blood type AB, since one allele isnt dominant over the other one
69
The allele IO in blood groups is... which means
It is recessive, so if mixed with the other alleles the blood group of the other one is shown. The only way to have blood group O is having two of these alleles.
70
The two causes of variation that influence phenotype
Genetic variation and Environmental variation
71
Genetic variation can occur through
Organisms in a species having different alleles
Sexual reproduction which results in different combinations of alleles
72
Environmental varaition occurs through
The conditions that the organisms is exposed to, which leads to acquired characteristics
73
Different alleles arise through
Genetic mutation. This is a change to the base sequence of DNA.
74
Most mutations dont
Have any effect on the phenotype. Some have a small effect and rarely a single mutation will significantly affect the phenotype.
75
The human genome project managed to
Map over 20000 genes in the body
76
3 medical applications of the human genome project
Prediction and prevention of disease
Testing and treatment for inherited disorders
New and better medicines
77
Possible drawbacks of the HGP
Increased stress due to increased knowledge of possible future disease
Pressure to not have children due to genetic problem
Discrimination by employers or insurers
