Genetics Part 2 Flashcards
What is a test cross?
A organism of unknown genetic type is crossed with a recessive gene example to workout its genotype.
What is selective breeding?
Choosing animals with a desired genetic trait and breeding them together.
What is cloning
Asexual reproduction which produces offspring identical to the parent and siblings.
Name the four bases the genes are made of.
Adenine, Cytosine, Guanine, Thymine.
Fruit flys have 8 chromosomes in its body cells, how many will be in its sex cells?
4
A horse has 33 chromosomes in its sex cells. How many will it have in its body cells?
66
What is the process replication in cells?
Chromosomes make copies of themselves.
What paired sequence would match this sequence of DNA have? C T A G T G C T
G A T C A C G A
Describe the percentage genotypes produces by this cross
50% DD and 50% Dd
Which of the following Chromosome combinations is male?
XX or XY
XY
What is the chromosome combination of a female?
XX
What is the main function of chromosomes?
To carry the inherited material of the organisim.
What is the main function of a gene?
To code for a particular trait e.g. hitch-hikers thumb
List advantages of selective breeding possible in cattle?
Increased milk production, better meat quality, faster growth rates, more offspring per birth, drought resistance etc.
What is a Chromosome?
A thread like strucuture found in the nucleus of cells
Why are siblings different from one another?
- Crossing over and independent assortment during meiosis creates unique combinations of genes from parents.
- Random fertilisation of sex cells.
What type of cells are produced during meiosis?
Gametes / sex cells
What type of cells are produced during mitosis?
Body cells for growth and repair.
Describe the cells produced by meiosis.
Four unique sex cells/ gametes each with half the chromosomes of the parent cell.
Describe the cells produced by mitosis.
Two genetic identical cells with the same number of chromosomes as the parent cell.
Describe the genotype percentages for the Punnet square below.
100 % Rr
Describe the genotype percentages for the Punnet square below.
25% TT
50% Tt
25% Tt
Describe the genotype percentages for the Punnet square below.
50% Cc
50% cc
What sequence would pair opposite to match this sequence of DNA?
A T C G A G C T
T A G C T C G A
What does ‘semi-conservative replication’ mean?
When chromosomes replicate on strand of DNA is original and the other is new.
What is a recessive gene?
A gene which is not expressed as often in a population.
What is a dominant gene?
The gene which is expressed even if a recessive gene is present.
What does ‘homozygous’ refer to?
The fact that alleles for a gene are the same, e.g. TT or tt
What letters are used to denote that sex chromosomes?
X and Y
Describe the genotype percentages for the Punnett square below.
25% SS
50% Ss
25% ss
What is the name given to describe alternative versions of a gene?
Alleles
What does the word ‘sibling/s’ mean?
The brother/s or sister/s
What is a phenotype?
The physically observable expression of a genotype, e.g. curly hair, attached earlobes, etc.
What is a genotype?
The actual alleles an organism possesses, e.g. BB, Dd, kk, etc.
What are the three substances that create a nucleotide?
Phosphate, sugar and base.
Describe the base pairing rules.
A pairs with T
C pairs with G
(and visa versa)
What does ‘heterozygous’ refer to?
Alleles for a gene are different e.g. Tt, Ss or Ff ect.