Genetics Flashcards
(126 cards)
1
Q
Define mutations
A
Change in structure of DNA in which new phenotypes are formed. This can make them better or less adapted to survival
2
Q
What is the base pair rule?
A
Adenine to Thymine and Cytosine to Guanine
3
Q
What are chromosomes made up of?
A
60% protein and 40% DNA
4
Q
Where is RNA made?
A
Nucleus
5
Q
What is the chemical nature of enzymes?
A
Protein
6
Q
What is the name of the backbone in double stranded DNA?
A
Phosphate-sugar backbone
7
Q
What type of sugar is present in DNA?
A
Deoxyribose
8
Q
How many types of DNA are there?
A
One
9
Q
Give an example of a chromosome mutation
A
Down’s syndrome
10
Q
What are the names of the different types of RNA?
A
rRNA - ribosmal
mRNA - messenger
tRNA - transfer
11
Q
How are mistakes made in genes?
A
By a mutation in replication
12
Q
Give some examples of a gene mutation
A
*Albinism
* Cystic fibrosis
* Sickle cell anaemia
13
Q
What is your reasons for blending the mixture for three seconds in your experiment to isolate DNA from a plant tissue?
A
- Breaks down cell walls
*Max. three seconds so DNA doesn’t break down
14
Q
What two nucleotides are pyrimidines?
A
Thymine and cytosine
15
Q
Give a characteristic of mutant alleles in a population
A
- Random occurence
- Low frequency
- Disadvantageous
- Advantageous
16
Q
Give some examples of disorders that arise from mutations (+diagram)
A
- Sickle cell anaemia
- Cystic fibrosis
17
Q
Define species
A
Group of organisms that can interbreed and produce fertile offspring
18
Q
Draw a diagram to show DNA replication
A
See notes
19
Q
What is your reason for using protease in your experiment to isolate DNA from a plant tissue?
A
Breaks down histone proteins that surround DNA
20
Q
Define start codon
A
3 bases that code for the signal to start transcription
21
Q
What is your reason for adding ice cold ethanol in your experiment to isolate DNA from a plant tissue?
A
DNA precipitates so it is visible
22
Q
Give an example of a coding structure
A
Base sequences
23
Q
Where is RNA found?
A
Nucleus and cytoplasm
24
Q
Explain how transcription occurs
A
- Double helix unwinds at a certain site of the gene that is to form a protein
- Bases (RNA nucleotides) attach to their exposed DNA bases (DNA is acting like a template)
- RNA bases join together using the enzyme RNA polymerase (catalyses the reaction) to make mRNA
- mRNA moves into the cytoplasm
25
Draw a diagram to show double stranded DNA
See notes
26
Describe some applications of DNA profiling
* **Finding the parent of a child**: Comparing the DNA of a child to that of a potential parent
* **Crime scene forensics**: By comparing the DNA at a crime scene with a possible suspect/victim
27
Define transcription
mRNA is formed using a single strand of DNA (DNA acts like a template) in the nucleus using RNA polymerase (enzyme).
28
Explain the steps of DNA replication
* DNA unwinds
* Enzyme (helicase) breaks bond between bases
* Free nucleotides from the cytoplasm move into the nucleus and join with their complimentary exposed bases on the DNA
* DNA polymerase binds the nucleotides together
* DNA rewinds (half old/half new strand) - 2 copies of DNA
29
Where does transcription occur?
Nucleus
30
Where is RNA found in the cell and no DNA?
Cytosol and ribosome
31
What is the reason for chopping the fruit in your experiment to isolate DNA from a plant tissue?
Increased surface area and breaks down cell walls
32
Define coding DNA
Carries code to produce a protein
33
Define gene
A short section of DNA that codes for a protein
34
Explain how translation occurs
* mRNA attaches to a ribosome (made of rRNA)
* tRNA in the cytoplasm bring an amino acid to the ribosome and bind to mRNA
* Matching codons on mRNA bond with anti-codons on the tRNA until they reach a stop codon
* Amino acids join in the right order to make a protein (by peptide bonds )
* Proteins form a functional shape by folding (globular)
35
How many hydrogen are there between each base pair
A(2)T and C(3)G
36
Describe the experiment to isolate DNA from a plant tissue (+diagram)
* Add washing up liquid and salt to a graduated cylinder and stir
* Add chopped onion to a beaker. Pour in the salt washing up liquid and stir
* Stand the beaker in a water bath at 60 degrees celsius for 15 minutes
* Cool the mixture by standing the beaker in an ice bath for 5 minutes
* Blend the mixture for no more than 3 seconds
* Filter the blended mixture through coffee filter paper
* Add 2-3 drops of protease enzyme to onion extract
* Very carefully, pour ice cold ethanol onto the surface of the onion extract
* DNA forms at the interface of the ethanol and extract
* Draw the DNA out of the solution by wrapping it around a glass rod
37
Give some examples of a mutagen
* Radiation - x-rays
* UV rays
* Chemicals - smoking cigarettes, asbestos
* Biological agents: Viruses, bacteria
38
Define genetic code
Sequence of bases that code for a protein
39
Explain the different types of RNA
* mRNA - messenger - carries the code to make a protein
* rRNA - ribosomal - makes the ribosome
* tRNa - transfer - carries an amino acid to the ribosome
40
Define amino acid codon
Codes for an amino acid
41
Where does DNA replication occur?
Nucleus
42
Who identified DNA?
Watson and Crick
43
What are the two base pairs present in DNA?
A-T and C-G
44
What are the base pairs present in RNA?
A-U and C-G (Uracil instead of Thymine)
45
What is your reason for using coffee filter paper in your experiment to isolate DNA from a plant tissue?
Bigger pores for DNA to pass through
46
Define triplet/codon
Sequence of three bases on DNA/RNA which code for an amino acid/start/stop
47
Draw a diagram to show a nucleotide with a purine base
See notes
48
How do mutations occur?
When DNA fails to replicate properly or proteins can't be made
49
What is the name of the sugar present is RNA?
Ribose
50
Define complementary in the context of DNA structure
Two bases joined together by hydrogen bonds. Purine with a pyrimidine
51
What two nucleotides are purines?
Adenine and guanine
52
Define mutagen
Agent that causes mutations
53
Why is DNA replication important?
* So mitosis can occur
* Make identical cells
54
How much of DNA is non-coding
97%
55
Define genetic screening
DNA is tested for a presence or absence of a particular gene or an altered gene.
56
Define allele
Alternate form of a gene
57
Where does translation occur?
Cytoplasm - ribosome
58
Define exons
Coding genes
59
What is the reason for adding washing up liquid in your experiment to isolate DNA from a plant tissue?
It breaks down the cell and nuclear membranes
60
Where is DNA found?
Nucleus
61
Define stop codon
3 bases that code for the signal to finish transcription of a gene
62
What is your reason for passing your mixture through a filter in your experiment to isolate DNA from a plant tissue?
Separates out DNA and proteins
63
What is the reason for adding salt in your experiment to isolate DNA from a plant tissue?
To clump DNA
64
Give examples of non-coding structures
Sugar and phosphate
65
What shape is RNA?
Single stranded
66
What are DNA nucleotides made up of?
Phosphate, 5C deoxyribose sugar and a nitrogenous base
67
What is the overall shape of DNA?
Double helix - parallel double stranded
68
Define gene
Section of DNA that codes for a protein
69
Describe the two types of mutations
**Gene mutation**: Effects on a small section of DNA
**Chromosomes mutation**: Large section of DNA/extra chromosome
70
What does DNA stand for?
Deoxyribonucleic acid
71
What is your reason for using a glass rod in your experiment to isolate DNA from a plant tissue?
To gently lift out the DNA
72
Define introns
Non-coding genes
73
When does DNA replication occur?
Interphase
74
Draw a diagram to show a nucleotide with a pyrimidine base
See notes
75
What is the enzyme in DNA?
DNA polymerase
76
What does the enzyme in DNA do if mutations occur?
Repair mutations
77
Define non coding DNA
Does not carry the code to produce a protein
78
What is your reason for putting your mixture in an ice bath in your experiment to isolate DNA from a plant tissue?
Prevents remaining enzymes destroying DNA
79
What is the term used to describe abnormal or altered DNA?
Mutations
80
What is a ribosome made of?
rRNA and protein
81
How are DNA profiles prepared?
* DNA is released (same as experiment)
* DNA is cut into fragments using a restriction enzyme
* Fragments are separated according to size (gel electrophoresis)
82
Define phenotype
Physical appearance
83
Define gene expression
The precise way that information in the genetic code in a gene is decoded to the cell and used to make a protein
84
Define nucleotide
Subunit of DNA
85
What is the reason for putting your mixture in a water bath at 60 degrees celsius in your experiment to isolate DNA from a plant tissue?
Denatures enzymes that would usually break down DNA
86
Define DNA profile
Making a unique pattern of bands from the DNA of a person - this can be used to tell different people apart by using their DNA
87
Define variation
Differences among a species
88
How is genetic variation caused?
* Sexual reproduction
* Mutations
* Environmental changes
89
Define acquired variations
Not passed on from generations
90
Define inherited variation
Passed on from parents to offspring (using genes)
91
Define evolution
Inheritable change within a population in response to change in the environment by natural selection over time
92
Name the two scientists involved in evolution
Darwin and Wallace
93
Describe the theory of evolution by natural selection
* High reproductive rates (or overbreeding)
* Competition (or struggle for survival
* Better adapted to survive (Survival of the fittest)
* The survivors reproduce (or breed)
* Others die out
* The genes of the most succesful are passed on
* Organisms with beneficial characteristics will dominate
94
What evidence is there of evolution?
* Fossils
* Comparative anatomy
* Comparative embryology
95
Layout of a genetic cross
Parents:
Gametes:
Offspring:
96
In rabbits, white coat (W) is dominant over black coat (w). Give the genotype and phenotype of the offspring of a crossinvolving two rabbits whose genotypes are (WW) and (ww)
See notes
97
Define incomplete dominance
Neither allele is dominant or recessive with respect to the other
98
Give an example of incomplete dominance
Flower colour in the snapdragon. Rr produces red flowers, rr produces white flowers, Rr produces pink flowers
99
Flower colour in snapdragons shows incomplete dominance i.e the heterozygous condition (Rr) is pink. Give the phenotypes for the F1 generation of the crosses between a red flowered plant and a white flowered plant
See notes
100
How many sex and non-sex chromosomes are present in a human cell
44 non-sex chromosomes, 2 sex chromosomes
101
How many chromosomes in the nucleus of each human cell?
46
102
Define autosomes
Chromosomes that do not determine sexuality
103
Give an example of features that autosomes dictate
Skin colour, number of arms
104
What are the names of the two sex chromosomes
X and Y
105
Which sex chromosome is longer
X
106
What sex chromosomes indicate a person is female
XX
107
What sex chromosomes indicate a person is male
XY
108
Give an example of animals where sex determination is reversed
Birds, butterflies and moths
109
Show by means of a cross why the father determines the sex of the child
See notes
110
What is Mendel's 2nd Law?
The Law of Independent Assortment: Either member of a pair of alleles can combine with either member of another pair of alleles -> Dibhybrid cross
111
Define gamete
Sex cell
112
Define fertilisation
Fusion of the male and female gametes to form a zygote
113
Define somatic cell
Non-sex cell
114
Define gene
Piece of DNA that codes for a protein
115
Define allele
Different forms a gene (represented by letters)
116
Define dominant
Masks expression of the recessive allele... usually represented by a capital letter
117
Define recessive
Only expressed if homozygous - masked by the dominant allele... represented by lower case letter
118
Define genotype
Genetic makeup
119
Define phenotype
Physical appearance
120
Define homozygous
Two alleles of a gene are the same eg. TT, tt
121
Define heterozygous
Two allels of a gene are different eg. Tt
122
Define monohybrid
One gene
123
Define dihybrid
Two genes
124
Define progeny
Offspring
125
**Flour Beetle**
Key:
* Black eyes (B) dominant for pearl eyes (b)
* Brown body (S) dominant for sooty body (s)
Show by means of a cross the offspring of: Black eyed, brown beetle (heterozygous) and pearl eyed, sooty beetle
See notes
126
