Biotechnology, genetics, mutations

Question 1

Causes of variation

Answer 1

mutations: Spontaneous mutations (DNA replication or cell division), mutagens, action of biological agents
Sexual reproduction (meiosis): crossing over, independent assortment, random fertilisation
Environmental factors

Question 2

Types of mutagens

Answer 2

Physical mutagens
Chemical mutagens
Biological mutagens

Question 3

Types of mutations

Answer 3

Point mutation: substitution: Synonymous, misense, nonsense. Frameshift: insertion or deletion
Chromosome: Monoploidy, polyploidy, Aneuploidy:trisomy, monosomy.

Question 4

Substitution mutation

Answer 4

occurs when a nucleotide is replaced by another
Single nucleotide polymorphins (SNP), difference between sequences of just one nucleotide
synonymous (silent)
Missense
nonsense

Question 5

Synonymous mutation (silent)

Answer 5

occurs when substituted base results in a codon that codes for same AA as OG codon

Question 6

Missense mutation

Answer 6

When SNP changes the amino acid

Question 7

Nonsense mutation

Answer 7

SNP creates a new stop codon within OG gene sequence
Results in production of incomplete polypeptide

Question 8

frameshift mutation

Answer 8

The reading from for corresponding AA has been nudged away from OG.
all codons downstream are affected.
Caused by insertion or deletion

Question 9

Insertion

Answer 9

addition of one or more nucleotides at a site within the original gene sequence

Question 10

Deletion

Answer 10

loss of nucleotides from a site within the original gene.

Question 11

Effects of mutations on survival

Answer 11

neutral mutations
Deleterious mutations
beneficial mutations

Question 12

Neutral mutations

Answer 12

protein product unchanged
Survival unaffected
synonymous and missense

Question 13

Deleterious mutations

Answer 13

result in production of an incomplete protein that is non-functional
Non-sense mutations

Question 14

beneficial mutations

Answer 14

New allele that benefits survival of organism
missense or nonsense

Question 15

Mutagens

Answer 15

physical
chemical
Biological

Question 16

physical mutagens

Answer 16

High energy radiation causes damage to DNA
Can cause change to nucleotides, distorting double helix, disrupts complementary base pairing.
Double strand break - complete break in chromosomes

Question 17

chemical mutagens

Answer 17

Causes substitution of one nucleotide for another
5-bromouracil - resembles thymine and can become incorporated in DNA, it can bind to any base pair. Thus changing what DNA codes for.

Question 18

Biological agents

Answer 18

Due to action of invasive pathogens: viruses and bacteria
DNA of pathogens can be permanently integrated into host cell’s DNA
Agrobacterioum - causes crown gall disease in stems of plants. Inserts plasmid into plant cell. (Ti plasmid), Codes for enzyme that cuts host DNA and inserts Ti into host DNA, host DNA modified by horizontal gene transfer. Causes rapid cell division.

Question 19

Monoploidy

Answer 19

Has 1 copy of each chromosome

Question 20

Polyploid

Answer 20

one or more complete extra sets of chromosomes

Question 21

Aneuploidy

Answer 21

Addition or loss of one chromosome from a cell
caused by non-disjunction
Trisomy -> one extra Monosomy -> one missing

Question 22

test cross

Answer 22

If organism’s genotype is unknown, and is displaying a dominant phenotype, it is possible to predict the genotype by performing a test cross.
involves crossing the individual whose genotype is unknown but that has a dominant phenotype with an organism that is homozygous recessive at the locus.

Question 23

Dihybrid cross

Answer 23

involve two genes wt 2 different alleles for one gene
(Eg. Tall, purple)
Punnet square structure: TP, Tp, tP, tp

Question 24

polygenic inheritance

Answer 24

Polygene - genes that have a small additive effect on a phenotype. Each gene consists of multiple alleles
inheritance of more than one gene that affects the inheritance of a single characteristic.

Question 25

Continuous variation

Answer 25

the condition of showing a range of phenotypes

Question 26

2 types of dominance

Answer 26

Incomplete dominance (partial dominance): occurs when 2 different alleles are present, but neither allele is completely dominant, both alleles contribute to phenotype, but partially. A third intermediary phenotype is observed. Codominance: Occurs when 2 alleles are completely dominant.

Question 27

External factors

Answer 27

external factors: (eg. Temperatures, pH, food availability, light exposure) Internal factors: (eg. Action of hormones) factors don’t change genome, only affects gene expression.

Question 28

Epigenetics

Answer 28

study of inheritable changes in gene expression without a change in the DNA sequence. Environmental factors can contribute to the addition or subtraction of epigenetic chemical factors and turn certain genes ‘on’ or ‘off’, can affect chromatin and gene expression. affects gene expression.

Question 29

Variations in chromosome structure

Answer 29

deletions: double-stranded breaks at two points and section in between drops out. Results in shorter chromosome, segment missing. Inversions: two breaks, segment in break flips and slides Translocation: section of chromosome breaks off and reattaches to another chromosome Duplications: extra copy made of a section and inserted into OG or other chromosome.

Question 30

increasing variation

Answer 30

Crossing over independent assortment Random fertilisation