Chromosomes
How many chromosomes do human cells have?
23 pairs
Define homozygous
Both alleles are the same in the genotype
What is complementary base pairing?
A with T, and C with G
What do pedigree charts show/what are they used for?
Showing a family tree
What is the difference between sexual and asexual reproduction?
Asexual needs only one parent- cloning
Sexual needs male and female
What hold chromosomes together?
Chromotids
Define heterozygous
The alleles in the genotype are the same
What is the purpose of DNA replication?
To produce another strand of DNA so that every cell has its own complete copy of DNA
Do circles or squares normally represent males?
Squares
Define mutation
Permanent change in the base sequence of DNA
What does DNA stand for?
Deoxyribonucleic Acid
What percentage of offspring will show the dominant phenotype when two recessive parents are crossed?
0%
What are the components of a nucleotide?
Base, sugar, phosphate
What do shapes of the same colour symbolise?
4
Where are chromosomes located?
In the nucleus
What percentage of offspring will be heterozygous when two heterozygous parents are crossed?
50%
Define semi-conservative replication
One half of the DNA molecule is kept in tact
Could two parents showing the dominant phenotype have an offspring that shows the recessive phenotype? Explain why/why not
Yes- they could both be heterozygous passing on their recessive allele meaning the offspring gets two recessive alleles in their genotype and therefore shows it in their phenotype
Why is variation important?
Means evolutionary change can occur and helps the species to survive in a changing environment.
Chromosomes are made up of...?
DNA
What is the genotypic ratio when two heterozygous parents are crossed?
1:2:1
What is the difference between the leading and the lagging strand?
Leading can be made continuously, whereas the lagging has to be made in Okazaki fragments
How do you tell the difference between offspring and mates?
Offspring come from the vertical line, whereas mates are horizontal lines
What are the two steps in meiosis that cause variation?
Crossing over- swapping of alleles when chromosomes cross over
Independent assortment- when homologous chromosomes line up randomly during meiosis