B16 inheritance Flashcards
what are chromosomes made of
- DNA
- containing genetic information in the form of genes
define gene
length of DNA that codes for a protein
define allele
alternative form of a gene
describe the inheritance of sex in humans
- sperm cell contains one X OR Y chromosome
- egg cell contains one X chromosome
- sex of child depends on sperm. if Y male, if X female
males have one X chromosome and one Y chromosome, XY
females have two X chromosomes, XX
describe what is meant by a haploid nucleus
contain single set of chrommosomes
describe what is meant by a diploid nucleus
contain two sets of chromosomes
chromosomes in diploid cell
- pair of each type of chromosome
- in human diploid cell, 23 pairs
describe what is meant by mitosis
- nuclear division
- giving rise to genetically identical cells
state the role of mitosis
- growth and repair of damaged tissues
- replacement of cells
- asexual reproduction
process of mitosis
- exact replication of chromosomes
- copies of chromosomes separate
- chromosome number in each daughter cell maintained
function of meiosis
involved in production of gametes
describe what is meant by meiosis
- reduction division
- chromosome number halved from diploid to haploid
- results in genetically different cells
where does meiosis occur
male testes and female ovaries
describe what is meant by inheritance
- transmission of genetic information
- from generation to generation
describe what is meant by genotype
- genetic make-up of an organism
- in terms of its alleles present
describe what is meant by homozygous
have 2 identical alleles of a particular gene
define pure-breeding
2 identical homozygous individuals that breed together
describe what is meant by heterozygous
have 2 diff alleles of particular gene
will heterozugous individual be pure-breeding?
no
describe what is meant by a dominant allele
allele that is expressed if it is present in the genotype
describe what is meant by a recessive allele
allele that is only expressed when there is no dominant allele of the gene present in the genotype
how to represent dominant allele
capital letter
how to represent recessive allele
lowercase letter
what is a monohybrid cross
- breeding of 2 individuals
- that differ in their alleles for a particular gene
what does a square represent in a pedigree diagram
male
what does a circle represent in a pedigree diagram
female
how are individuals who show inherited characteristics represented in pedigree diagram
coloured symbol
how are individuals who do not show inherited characteristic shown
white symbol
define carrier
individual who carries one copy of a recessive allele for a genetic characteristic
how is a carrier shown on a pedigree diagram
partly shaded symbol
