17 Inheritance Flashcards
chromosomes
made of DNA: which contains genetic information in the form of genes
gene
a length of DNA that codes for a protein
Allele
alternate form of gene
describe the inheritance of sex in humans
out of 23 pairs of chromosomes, 1 pair determines the sex of the individual. Males have XY and females have XX.
what determines the sequences of amino acids used to make a specific protein
the sequences of bases in a gene
Explain that different sequences of amino acids give different shapes to protein molecules
How does DNA control cell function
By controlling the production of proteins, including enzymes, membrane carriers and receptors for neurotransmitters
Explain how a protein is made:
- the gene coding for the protein remains in the nucleus
- messenger RNA (mRNA) is a copy of a gene
- mRNA molecules are made in the nucleus and move to the cytoplasm
- the mRNA passes through ribosomes
- the ribosome assembles amino acids into protein molecules
- the specific sequence of amino acids is determined by the sequence of bases in the mRNA
Why, even though the body cells in an organism contain the same genes, not all are expressed?
Beacuse the cell only makes the specific proteins it needs
haploid nucleus
a nucleus containing a single set of chromosomes
diploid nucleus
a nucleus containing two sets of chromosomes
What’s in a diploid cell
A pair of each type of chromosome and in a human diploid cell there are 23 pairs
mitosis
nuclear division giving rise to genetically identical cells
role of mitosis
growth, repair of damaged tissues, replacement of cells and asexual reproduction
what occurs before mitosis
the exact replication of chromosomes
what occurs during mitosis
the copies of chromosomes seperate, maintaining the chromosome number in each daughter cell
stem cells
unspecialised cells that divide by mitosis to produce daughter cells that can become specialised for specific functions
meiosis
a reduction division in which the chromosome number is halved from diploid to haploid ruslting in genetically different cells
what process is involved in the production of gametes
meiosis
inheritance
the transmission of genetic information from generation to generation
describe genotype
the genetic make up of an organism (and in terms of the alleles present)
describe phenotype
the observable features of an organism
describe homozygous
two identical alleles of a particular gene
pure breeding
when two identical homozygous individuals breed together
describe heterozygous
having two different alleles of a particular gene
what type of inidividual will not be purebreeding?
a heterozygous individual
dominant allele
an allele that is expressed if it is present in the genotype
recessive allele
an allele that is only expressed when there is no dominant allele of the gene present in the genotype
3 Explain how to use a test cross to identify an
unknown genotype
by crossing two parents to see the phenoypic ratio of the offspring produced.
- a homozygous recessive individual should be crossed with the unknown genotype individual
Codominance
a situation in which both alleles in heterzygous organisms contribute to the phenotype
Which blood types are dominant and which are recessive?
A and B are dominant. O is recessive.
sex-linked characteristic
a feature in which the gene responsible is located on a sex chromosome and that this makes the characteristic more common in one sex than in the other
example of sex linkage
red-green colour blindness
