Zusammenfassung der Ressource
OCR 21st Century B1
- Genes
- A section of DNA giving the
instructions for a cell about how
to make a certain type of protein
- structural (e.g.
collagen)
- functional (e.g. enzymes
such as amylase)
- All the instructions to control how
an organism develops and
functions are found in the nucleus
of its cells and are called genes
- genes are sections of DNA
molecules that make up
chromosomes in the nuclei of cells
- You and Your Genes
- Clones
(individuals with
identical genes)
- Bacteria, plants and
some animals can
reproduce asexually
to form clones
- Differences between
clones are due to
environmental
factors
- Plants-
Bulbs or
runners
- Animals- artificially,
when the nucleus from
an adult body cell is
transferred to an empty
unfertilised egg cell
- Stem Cells
- Adult stem cells which
are unspecialised cells
that can develop into
many different types.
- unspecialised stem cells
have the potential to
produce cells needed to
replace damaged tissues
and therefore can be
used to treat some
diseases and illnesses
- brain cells=Parkinsons
- spinal damage, diabetes, skin grafts, liver damage
- bone marrow=
leukaemia. Develop
into blood cells only
- Embryonic stem cells-
Any gene can be
switched on during
development to
produce any type of
specialised cell
- Animals- When
cells of an embryo
separate (identical
twins) via mitosis
- majority of cells of multicellular
organisms become specialised during
the early development of the organism
- Characteristics
- determined
by genes
(e.g.
dimples)
- determined by
environmental
factors (e.g. scars)
- combination of
genes and the
environment
(e.g. weight)
- determined by several
genes working together
(e.g. eye colour)
- Chromosomes
+ Allelles
- Body cells contains 23
pairs of chromosmes
- Gametes contain 23
individual chromosomes
- Chromosomes in a pair carry
the same genes in the same
place, but that there may be
different versions of genes
called alleles .
- When a sperm cell
fertilises an egg cell,
their nuclei join up. The
fertilised egg cell now
has 23 pairs of
chromosomes in total
- Variation- Each gametes contains
a different mixture of alleles
from each parent due to crossing
over in the process of meiosis.
- an individual usually has
two alleles for each gene
- Male
- F
e
m
a
l
e
- The Y chromosome triggers
the development of testes,
and that in the absence of a Y
chromosome ovaries develop
- genotype
describes the
genetic make-up
of an organism
(the combination
of alleles)
- phenotype
describes the
observable
characteristics
that the
organism has.
- Diseases and Inheritence
- A small number of
disorders are
caused by faulty
alleles of a single
gene, including
Huntington’s
disease and cystic
fibrosis
- Huntington’s disease
– late onset, tremor,
clumsiness, memory
loss, inability to
concentrate, mood
changes
- Caused by a
dominant allele
- Cystic fibrosis – thick
mucus, difficulty
breathing, chest
infections, difficulty
in digesting food
- Caused by a
recessive alleles
- a person with one recessive allele is a
carrier and can pass the recessive
allele to their children. They won't
show the symptoms seen here
- Genetic testing
- predictive testing
for genetic diseases
- Testing embryos for
embryo selection
(pre-implantation
genetic diagnosis)
- Life
decisions
- Whether to
terminate a
pregnancy
- Whether to
have children
- Societal
- Getting life
insurance
- employment
implications
- freedom of
information
- Preparation
- Tell family
- Councilling
for stress
- Religious
implication
- Preparation
for newborn
- Treatment
possibilities
- Risks
- Foetal
Damage/
infection
- Chance of
miscarriage
- False Negatives- failed to
detect a certain allele or
faulty chromosome
- False
positives-wrongly
detected a certain
allele or faulty
chromosome.
- testing an
individual before
prescribing drugs