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40 Cards in this Set
- Front
- Back
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What is variation?
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Differences between individuals of the same species
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Genes occur in...
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long stands called chromosomes
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Where are genes located?
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In the nucleus of every cell
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What are chromosomes made of?
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DNA molecules
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What are DNA molecules?
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Two very long strands of DNA coiled together to make a double helix
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What instructions do DNA molecules have?
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How the organism should be constructed and how each cell should function
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What do genes control?
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They control the development of different characteristics by issuing instructions to the cell
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What can proteins that form inside cells be?
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Structural proteins (cell growth and repair) or functional proteins (speed up chemical reactions)
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Chromosomes usually come in...
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Pairs
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How many pairs of chromosomes do human cells have?
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23 pairs of chromosomes (46 in total)
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How many chromosomes do the sperm/egg cell contain?
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23 single chromosomes
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A gene can have different versions called...
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Alleles
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For each gene, how many alleles do you inherit?
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One from your mum and one from your dad, so 2 in total.
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What are two alleles that are the same called?
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Homozygous
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What are two alleles that are different called?
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Heterozygous
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What is the combination of alleles you have called?
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Your genotype
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What is the phenotype?
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The characteristics you actually show
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What's a dominant allele?
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The dominant allele controls the development of a characteristic, even if it's present on only one chromosome pair
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What is the recessive allele?
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The recessive allele controls the development of a characteristic only if a dominant allele is not present
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XX represents?
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Female
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XY represents?
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Male
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What's the name on the gene that determines the sex of the individual?
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The sex-determining region Y (SRY) gene
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What does Huntington's Disorder affect?
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The central nervous system
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How is HD caused?
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It's caused by a faulty allele on the fourth pair of chromosomes
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What does Cystic Fibrosis affect?
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It affects the cell membranes causing an overproduction of thick and sticky mucus, especially in the lungs, pancreas and gut
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What are the symptoms of Cystic Fibrosis?
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Weight loss, difficulty in breathing, chest infections and difficulty in digesting food(eating)
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What is meant by a carrier of a genetic disease?
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It's when a person only possesses one allele so although they have no symptoms, they could pass it on to their offspring
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How can a fetus be tested for genetic disease?
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The fluid surrounding the fetus or placenta can tested by taking a sample of the amniotic fluid. It can cause miscarriage.
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What's a true positive?
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When the fetus actually has the disorder
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What's a true negative?
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When the fetus doesn't have the disorder
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What's a false positive?
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When the test results show that the fetus has the disorder when actually, it doesn't
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What's a false negative?
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When the test results show that the fetus hasn't got the disorder when actually, it does
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Why is embryo selection controversial?
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Some believe it's unnatural and against God. Also, pre-selection of a baby's characteristics could reduce variation
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What is asexual reproduction?
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Reproduction without the fusion on gametes (sex cells)
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How are animal clones produced artificially?
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The nucleus from an adult body cell is transferred into an empty unfertilised egg cell. The new individual will have exactly the same information as the donor
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What is a disadvantage of cloning?
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The new plants/individual will be susceptible to the same diseases as the parent
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What are embryonic stem cells?
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They are unspecialised cells and have the potential to develop into any kind of specialised cell
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What are adult stem cells?
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They have the potential to develop into a range of specialised cells, but not all types
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Where are embryonic stem cells taken from?
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They're taken from a developing embryo so to produce them, it's necessary to clone embryos
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Where are adult stem cells taken from?
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They're taken from areas that are adapted for the replacement and repair of tissues, such as the umbilical cord
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