Inheritance Flashcards
heredity
The
inheritance of such characteristics is called heredity
gentics
The
inheritance of such characteristics is called heredity
chromosome
A chromosome is a thread of DNA, made up of a string of
genes
gene
A gene is a length of DNA that codes for a protein
what is inside chromosome
Inside a nucleus are thread-like structures called
chromosomes which can be seen most clearly at the
time when the cell is dividing.
centromere
Each chromosome
has certain characteristics when ready to divide: there
are two chromatids, joined at one point called a
centromere
Each chromatid is a string of
genes,
coding for the person’s characteristics
A human body (somatic) cell nucleus contains
46 chromosomes
The
only pair that do not necessarily match is chromosome
chromosome
pair 23: the ‘sex chromosomes’
The Y chromosome is
much smaller than the
x chromosome
sex chromosomes
Whether you are a male or female depends on the
pair of chromosomes called the ‘sex chromosomes’
In females, the two sex chromosomes, called
the X chromosomes, are the same size as each
other XX
In males,he two sex chromosomes are of
different sizes. XY
mitosis
Mitosis is nuclear division giving rise to genetically
identicalcells.
why is mitosis importance
The processes of growth, repair and replacement
of cells all rely on mitosis.even if an organism is asexual
meiosis
Meiosis is nuclear division, which gives rise to cells that are
genetically different.
The process of meiosis takes place in
the gonads
of animals (e.g. the testes and ovaries of mammals,
and the anthers and ovules of fl owering plants). the cells formed are gametes.
an allele
is a version of a gene
Genotype
Genotype is the genetic make-up of an organism in terms of
the alleles present.
phenotype
Phenotype is the features of an organism
homozygous
Homozygous means having two identical alleles of a
particular gene e.g. TT, where T is tall. Note that two
identical homozygous individuals that breed together will
be pure-breeding
heterozygous
Heterozygous means having two different alleles of a
particular gene e.g. Tt. Note that a heterozygous
individual will not be pure breeding.
types of allele’s
An allele that is expressed if it is present is dominant.
An allele that is only expressed when there is no dominant
allele of the gene present is recessive.
co-dominant
If both genes of an allelomorphic pair produce their
effects in an individual (i.e. neither allele is dominant
to the other) the alleles are said to be co-dominant
