Topic 4 - Genetics (SL) Flashcards
What are chromosomes?
Made up of genes (made of DNA)
Proteins associated with DNA in eukaryotes
What is a gene?
A heritable factor that controls a specific characteristic
What is a gene locus?
The position of a gene on a chromosome
What is an allele?
A form of a gene, differing from other alleles of the gene by a few bases at the most and occupying the same locus as other alleles of that gene
What is gene mutation?
A change to the base sequence of a gene
What is a diploid cell?
Cell has two full sets of chromosomes
What is a haploid cell?
Have one set of chromosomes
What are homologous chromosomes?
Have the same genes as each other, in the same sequence, but not necessarily the same alleles of those genes
What is a karyotype?
The number and appearance of the chromosomes in an organism
Describe amniocentesis
Sample of amniotic fluid is removed from the amniotic sac around the foetus (hypodermic needle inserted through the wall of abdomen and walk of uterus)
Amniotic fluid drawn out in a syringe containing cells from the foetus
Describe chorionic villus sampling
Cells are removed from foetal tissues in the placenta called chorionic villi (hypodermic needle)
What is non-disjunction?
Non-separation of the chromosomes
Results in gametes being produced with one too many or too few chromosomes
Define homozygous
Having two identical alleles of a gene
Define heterozygous
Having two different alleles of a gene
Define dominant allele
An allele that has the same effect on the phenotype in a heterozygous individual as in a homozygous individual
