B1 - You And Your Genes Flashcards
(29 cards)
How many chromosomes are there in a gamete?
23 chromosomes
What is an allele?
A variation of the same type of gene.
Where are chromosomes found within a cell?
In the nucleus
True or false - in humans, chromosomes are usually found in groups of four?
False - they are found in pairs
How do genes control the different characteristics we develop?
They code for the proteins which structure our features and therefore the characteristics we display
What do the words ‘genotype’ and ‘phenotype’ mean?
Genotype = All of the genes in an organism Phenotype = The genes the organism displays
Is a person’s weight determined by genes, the environment or a combination of both?
Both
Name the two types of sex cell.
Egg cells and sperm cells
How many chromosomes are found in sex cells? And what are these cels called?
23 chromosomes
Gametes
Why do most children look a bit like both of their parents but not identical to either?
Because you receive half of your genes from both parents
What is the difference between homozygous and heterozygous?
Homozygous = both your alleles for that particular gene are the same e.g. AA Heterozygous = your alleles for that particular gene are different e.g. Aa
What sex chromosomes do human males have?
X and Y
How does a gene on one of the human sex chromosomes cause embryos to develop into males?
Because it codes for the protein which develops the testes and the rest of the male reproductive system.
Is the allele for cystic fibrosis dominant or recessive?
Recessive
What are the symptoms of cystic fibrosis?
- thick, sticky mucus
- difficulty breathing
- difficulty digesting food = often small and skinny
- chest infections =painful coughing
What are the symptoms of Huntington’s disease?
- Clumsiness
- Memory loss
- Poor concentration
- Mood changes
- Tremors (shaking)
What is the chance of a child inheriting Huntington’s disease if one of their parents has one copy of the faulty allele?
50%
During IVF treatment, what is the process of testing embryos to see if they have a genetic disorder called?
Pre-implantation genetic diagnosis
Other than testing embryos during IVF, give other uses of genetic testing.
- To check if you have a condition before antibiotics are prescribed to you and prevent adverse reactions
- Children and adults can be checked to see if they carry alleles for genetic disorders.
What happens to an embryo in IVF treatment of it carries a genetic disorder?
It is discarded.
Describe three issues surrounding genetic testing.
1- That all of the embryos have equal rights to life and should not be discarded
2- If someone in the family has a genetic disorder should all their relatives be tested?
3- If someone has a genetic disorder is it right for them to have children?
Write a definition of the word ‘clone’.
A clone is an organism with identical DNA to another.
They have the same genes and the same alleles of those genes.
How can bacteria reproduce asexually?
Their cells duplicate, doubling the population each time.
How can plants reproduce asexually?
Some plants produce horizontal stems called runners that move out from the base of the plant and form new clones at their tips e.g strawberry plants
Other plants produce underground fleshy structures called bulbs. These can then grow to form a new identical plant e.g garlic
