4.6.1 reproduction Flashcards
Sexual reproduction involves?
the joining (fusion) of male and female
gametes
in animals
sperm and egg cells
in plants
pollen and egg cells
what is there in sexual reproduction and what does it lead to?
In sexual reproduction there is mixing of genetic information which
leads to variety in the offspring
The formation of gametes involves?
gametes
Asexual reproduction involves
only one parent and no fusion of
gametes
in asexual reproduction, there is no mixing of genetic information. what does this lead to?
This leads to
genetically identical offspring (clones).Only mitosis is involved.
meiosis ?
halves the number
of chromosomes in gametes
fertilisation?
restores the full
number of chromosomes.
Cells in reproductive organs divide by?
meiosis to form gametes.
When a cell divides to form gametes:
copies of the genetic information are made
* the cell divides twice to form four gametes, each with a single
set of chromosomes
all gametes are?
genetically different from each other
Gametes join at fertilisation to?and the new cell divides by?
restore the normal number of
chromosomes.
The new cell divides by mitosis.The number of cells
increases
As the embryo develops?
cells differentiate
The genetic material in the nucleus of a cell is composed of
a chemical called DNA
what is DNA?
DNA is a polymer made up of two strands
forming a double helix
. The DNA is contained in structures called?
chromosomes
what is a gene?
A gene is a small section of DNA on a chromosome
what does a gene do?
Each gene codes for a particular sequence of amino acids, to make a specific
protein.
what is the genome of an organism?
The genome of an organism is the entire genetic material of that
organism
has the whole genome been studied?
The whole human genome has now been studied and
this will have great importance for medicine in the future.
what is he importance of
understanding the human genome?
search for genes linked to different types of disease
* understanding and treatment of inherited disorders
* use in tracing human migration patterns from the past.
Some characteristics are controlled by a single gene, such as:
fur
colour in mice; and red-green colour blindness in humans
different forms of the same gene is called?
alleles
The alleles present, or genotype, operate at?
a molecular level to
develop characteristics that can be expressed as a phenotype.
dominant allele
A dominant allele is always expressed, even if only one copy is
present
recessive allele
A recessive allele is only expressed if two copies are
present (therefore no dominant allele present)
homozygous
If the two alleles present are the same the organism is homozygous
for that trait
heterozygous
if the alleles are different they are heterozygous
In females the sex chromosomes are the same
(XX).
In males the chromosomes are different
XY
22 pairs control characteristics only, but one of the pairs carries the
genes that determine?
sex
