chapter 17: inheritance Flashcards
(20 cards)
describe chromosomes
thread like structures of dna carrying genetic information in the form of genes located in the nucleus
describe gene
a length of dna that codes for a protein
describe allele
an alternative form of a gene
inheritance of sex in humans
- depends on the father as he has a Y chromosome
- sex is determined by an entire chromosome pair
how is the shape of a protein molecule determined
- sequence of bases in a gene determines the sequence of amino acids used to make a specific protein
- different amino acids give different shapes to protein molecules
how does dna control cell functions
- controls the production of proteins (enzymes, neurotransmitter receptors), carrier proteins
describe protein synthesis
- gene coding for the protein is copied in the nucleus
- mRNA, copy of a gene, moves into the cytoplasm why the original gene stays in the nucleus
- mRNA passes through ribosome
- ribosome assembkes amino acids into protein
- specific sequence of amino acids is determined by the specific sequence of bases in the mRNA, determines the type of protein produced
why is it that most genes are not expressed in a particular cell?
most body cells in an organism contain the same genes, but many genes in a particular cell are not expressed because the cell only makes the specific proteins it needs
describe mitosis
- nuclear division giving rise to genetically identical cells
- used for asexual reproduction, growth, repair of damaged tissue, and replacement of cells
state the process of mitosis
- each chromosome in the nucleus copies itself exactly
- chromosomes line up along the centre of the cell where they are separated
- cell divides into two daughter cells where each new cell has a copy of each of the chromosomes
describe stem cells
- unspecialised cells that divide by mitosis to produce daughter cells that can become specialised for specific functions
- ultimate stem cell is zygote: every body cell except for gametes is from zygote
describe meiosis
- reduction division in which the chromosomes is halved resulting in genetically different cells
- involved in the production of gametes
— - each chromosome makes identical copies ot itself
- chromosomes pair up along centre of cell, recombinatiom occurs and cell splits
- happens again
- 4 haploid daughter cells produced
describe genotype
combination of alleles controlling each characteristic resulting in the genetic makeup of an organism
describe phenotype
the observable features of an organism
describe a dominant allele
an allele that is expressed if it is present in the genotype
describe a recessive allele
an allele that is expressed only when there is no dominant allele of the gene present in the genotype
describe monohybrid inheritance
- the inheritance of characteristics controlled by a single gene
how can an unknown genotype be indentified
- use a test cross
- cross the unknown individual with an individual showing the recessive phenotype
- if the recessive phenotype is shown, it must be homozygous recessive; if not, it is heterozygous
describe codominance
- situation in which both alleles in heterozygous organisms contribute to the phenotype
- blood group is an example for AB, as both the A and B alleles contribute to the phenotype and are expressed equally
describe a sex linked characteristic
- a feature in which the gene responsible is located on a sex chromosome, making the characteristic more common in one sex than the other
- red-green colour blindness, more prevalent in males
