Science Genetics And Inheritance Revision Flashcards
How many pairs of chromosones are there in every cell?
23 pairs of chromosones
How many chromosones come from the sperm cell?
23
How many chromosones come from the egg cell?
23
What is another name for the egg and sperm cells?
Gametes
What do you call the single cell created after the fusion of the gametes?
The Zygote
How many pairs of chromosones does the zygote have?
23
What does DNA stand for?
Deoxyribonucleic acid
What is variation?
The difference between individuals of the same species
What causes can variation be due to?
Genetic or environmental causes
Who were the main two people to discover DNA?
James Watson and Francis Crick
What is a gene?
A section of DNA
Does each chromosone from the parent have to have the same version of a gene?
No, it can be a different version of a gene
What do you call different versions of a gene that code for different versions of a charicatristic?
An allele
What is a homozygous allele pair?
When the alleles in a matching pair are the same
What is a heterozygous allele pair?
When the alleles in a matching pair are different
What is a dominant allele represented by?
Capital letter
What is a recessive allele represented by?
Lowercase letter
What is the allele pair for each charictaristic called?
The genotype
What is the physical expression of the allele pair called?
The phenotype e.g. Rr = red petal rr = yellow petal
Name two diseases linked with genetics
Cystic Fibrosis, Polydactyly
What is cystic fibrosis?
When a large amount of mucus builds up in the lungs and digestive system
Name 3 symptoms of cystic fibrosis.
Chest infections
Wheezing, coughing and damage to the airways
Yellowing of skin and whitening of eyes
Diarrhoea, constipation and large, smelly excrement
What is polydactyly?
When a baby is born with one or more extra fingers/toes.
Where on the hand/foot is the extra finger(s) located?
Next to the pinky finger or little toe
