Inheritance Flashcards
Chromosomes
made of DNA, which contains genetic information in the form of
genes.
A gene is a
a length of DNA that codes for a protein.
An allele is an
alternative form of a gene.
female chromosomes
XX
male chromosomes
XY
The sequence of bases in a gene determines the
sequence of amino acids used to make a specific protein.
Different sequences of amino acids give
different shapes to protein molecules.
DNA controls cell function by
controlling the production of proteins, including
enzymes, membrane carriers and receptors for neurotransmitters
How 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
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. For instance, the cells in salivary gland don’t need to make protease but they
have the gene for it which is not expressed because the cell doesn’t need it.
A haploid nucleus
is a nucleus containing a single set of chromosomes
A diploid nucleus
is a nucleus containing two sets of chromosomes
In a diploid cell,
there is 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
in growth, repair of damaged tissues, replacement of cells and
asexual reproduction.
Process of mitosis
The exact replication of chromosomes occurs before mitosis.
During mitosis, the copies of chromosomes separate, maintaining the chromosome
number in each daughter cell.
Stem cells is unspecialised cells that divide
by mitosis to produce daughter cells that
can become specialised for specific functions.
Meiosis is involved in the
production of gametes
Meiosis
reduction division in which the chromosome number is halved from
diploid to haploid resulting in genetically different cells
Inheritance
transmission of genetic information from generation to generation
Genotype
the genetic make-up of an organism.
Phenotype
the observable features of an organism.
Homozygous
having two identical alleles of a particular gene
Two identical homozygous individuals that
breed together will be pure-breeding.
Heterozygous
having two different alleles of a particular gene.
A heterozygous individuals will not be
pure-breeding.
dominant allele
is 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.
Codominance
a situation in which both alleles in heterozygous organisms
contribute to the phenotype
A 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(usually male) than in the other.
example of sex linkage.
Red-green colour blindness
