B1 - You And Your Genes Flashcards
(39 cards)
Give an example of a human characteristic determined only by genes
Eye colour, natural hair colour, blood group, dimples
Is height affected by genes, environmental factors, or both? Explain your answer
Height is controlled by both genes and environmental factors. For example if your parents are both tall then you’re likely to be tall. However, if you grow up in a place with a food shortage, you’ll be shorter than if you had all the food you needed.
Give an example of a human characteristic that is affected by the environment
Weight, height, skin colour, condition of teeth, academic or athletic ability
What is in the nucleus?
The ucleus contains genetic material. The genetic material in the nucleus is arranged in to chromosomes. The human cell nucleus contains 23 pairs of chromosomes. Each chromosome is one very long molecule of DNA that is coiled up. A gene is a short length of a chromosome. Genes control the development of different characteristics, for example hair colour and how an organism functions.
What are alleles?
Alleles are different versions of the same gene
What do genes code for?
Genes code for proteins. Proteins are the building blocks of cells. Having different versions of proteins means that we end up with different characteristics.
What is an organism’s genotype?
An organisms genotype is all of the genes it has
What is an organism’s phenotype?
The characteristics or physical features that an organism displays
Why are children never identical to one of their parents?
Children inherit half their chromosomes from their mother and half from their father. This means that they don’t get all of the same alleles as one of the parents, so they won’t look identical to them.
In terms of genes, why do people naturally have different coloured hair?
You can get different versions of the same gene, which give different versions of a particular characteristic. These different versions of genes are called alleles. There are different alleles of the gene for hair colour. The alleles that you have will determine your hair colour.
How does sexual reproduction in humans work, and how does it produce variation?
During sexual reproduction a sperm cell fertilises an egg cell. The fertilised egg cell contains a mixture of chromosomes - half from the mother, and half from the father. This means the offspring inherits a combination of alleles (and therefore features) from each parent, producing variation.
How is the number of chromosomes in a sex cell different from the number of chromosomes in a body cell?
Body cells contain 46 chromosomes - 23 pairs. Sex cells contain 23 chromosomes.
The allele for being a werewolf is recessive (w). Remus is a werewolf. What is his genotype? Explain why
For a recessive characteristic to show an individual must have both recessive allele is. This means we must must have to recessive werewolf alleles (ww). If he only had one recessive werewolf allele then the dominant allele ‘non-werewolf’ characteristic would be displayed.
Why do children often resemble their parents?
Children inherit half their chromosomes from their mother and half from the father. This means that they get some alleles from each parent, so will display some characteristics from each parent, for example a child may have their mum’s big nose, and their dad’s little ears.
Pink hair (H) is dominant over green hair (h) in giraffes. What colour hair would a giraffe with the genotype Hh have? Explain why
The giraffe will have pink hair, as the pink hair allele (H) is dominant over the recessive green hair allele (h).
What do the terms genotype and phenotype mean?
Genotype means what combination of alleles you have. Phenotype means the characteristic (physical feature) you display as a result of your genotype.
Define homozygous and heterozygous
Homozygous means you have two of the same alleles for that particular gene. Heterozygous means you have two different alleles for that particular gene.
Proteins can be structural or functional give an example of each type
Collagen is a structural protein. The enzyme amylase is a functional protein.
How does the presence of a Y chromosome cause an embryo to develop testes?
The Y chromosome (which is only present in males) carries a gene which causes a specific protein to be produced. This protein causes the testes to develop in an embryo. In the absence of this protein (no Y chromosome) the embryo develops ovaries.
Alex has an X chromosome and a Y chromosome. Is Alex a boy or a girl?
Alex is a boy. The Y chromosome causes male characteristics.
What symptoms will someone suffering from Huntington’s disease experience?
Having tremors, clumsiness, memory loss, inability to concentrate and mood changes.
Is the gene for Huntington’s disease dominant or recessive? Explain what your answer means in terms of inheritance of the disorder.
It’s dominant. The disorder can be inherited if just one parent carries the gene. (If the disorder was recessive both parents would need to have the faulty allele for there to be a risk of the child inheriting the condition). If a parent is a carrier, they are also a sufferer.
What symptoms will someone suffering from cystic fibrosis experience?
Difficulty breathing, producing a thick mucus, chest infections and difficulty digesting food.
What is the risk of carrying out a genetic test during pregnancy?
Genetic testing can increase the chance of miscarriage during pregnancy.
