B1 - You and Your Genes Flashcards
Phenotype
The characteristics which show up in our appearance
What environmental factors affect our characteristics?
- Climate
- Diet
- Physical accidents
- Culture
- Lifestyle
2 examples of characteristics controlled by genes:
- Dimples
- Height
Genome
The complete gene set of an organism
Put these in order of decreasing size: Gene, Chromosome, DNA, Nucleus
Nucleus -> Chromosome -> DNA -> Gene
What do genes do?
Carry the instructions that control how you develop and function. They tell cells which protein to make.
What is DNA make of?
4 chemicals called bases
The order of bases determines…
The order of amino acids in a protein
What are the two types of protein?
Functional and Structural
What do functional proteins do? Give 3 examples of said proteins
Enable the body to function: enzymes, antibodies and hormones
What do structural proteins do? Give 2 examples of said proteins
Give the body structure, rigidity and strength e.g collagen in ligaments and keratin in skin
What has the human genome project done?
Identified the location of all the genes on human chromosomes
How many chromosomes do human cell have?
23 pairs of 46 in total
How many chromosomes do sex cells have?
23
What are Alleles?
The different a forms in which genes controlling a characteristic can occur
Homozygous
When someone has two alleles of a gene which are identical
Heterozygous
When someone has two alleles for a gene which are different
Two types of allele
Dominant and Recessive
Punnet Squares are used to…
Show genetic crosses and find the probability of two parents producing different types of offspring
A family tree diagram is used to…
Show the inheritance of a trait in a family over several generations and trace a genetic disorder over generations
XX chromosomes are found in
Females
XY chromosomes are found in
Males
Genetic screening
A process used to check for a particular disease
Clones
Individuals with identical genes
3 examples of organisms which reproduce asexually
Bacteria, Some plants and Simple animals (e.g. Hydra)
Two ways plants can reproduce asexually & examples of plants which use each method
- By Using Runners (e.g. Strawberries) shoots sent out to grow into identical plants
- By Producing bulbs (e.g. Daffodils)
Advantages of cloning
- Successful characteristics are seen in offspring
- Asexual reproduction is useful where plants and animals live in isolation
Disadvantages of cloning
- There is no genetic variation
- If conditions change or a disease arises the population could be wiped out
2 animals which reproduce asexually
Starfish and Sea anemones
What are the two types of stem cell?
Adult and Embryonic
Adult stem cells
Are unspecialised cells which can develop into many (but not all) cell types
Embryonic stem cells
Unspecialised cells that can develop into any type of cell
Differentiation
When cells become specialised after the 8 cell stage
Why is the use of embryonic stem cells controversial?
-They are usually taken from unused embryos following fertility treatment and their use involves the destruction of the embryo
Stem cells could be used for:
- The testing of new drugs
- Understanding how cells become specialised in the early stages of human development but the switching on and off of genes
- Renewing damaged cells in spinal injuries, heart disease, Huntington’s and Parkinson’s
What are the 3 different types of cloning?
- Therapeutic cloning
- Embryo transplants
- Fusion cell cloning
Steps of therapeutic cloning:
- Nucleus taken out of a human egg cell
- Nucleus from a patient’s cell put into the egg cell
- Egg cell stimulated to develop into an embryo
- Stem cells taken from embryo
- Stem cells grown in a container of warm nutrients
- Stem cells treated to develop into required cell types
How are embryo transplants performed?
- A developing embryo is removed from a pregnant animal at an early stage before its cells have had time to differentiate.
- The cells are separated, grown for a whole in a laboratory the transplanted into host mothers.
- When the offspring are born they are not identical to their host mother but to each other and the original pregnant animal.
Steps of fusion cell cloning
- The nucleus from a body cell is extracted and inserted into an egg cell that has had its nucleus removed.
- This gives the egg cell a full set of genes without being fertilised.
- The embryo is implanted into a suitable surrogate mother.
Who is Dolly the Sheep?
The first mammal to be cloned using adult cell cloning. She was born in the Uk in 1996 and died in 2003.
Genotype
Our genetic makeup
