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40 Cards in this Set
- Front
- Back
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What is variation? |
Differences between individuals of the same species |
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Genes occur in... |
long stands called chromosomes |
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Where are genes located? |
In the nucleus of every cell |
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What are chromosomes made of? |
DNA molecules |
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What are DNA molecules? |
Two very long strands (of DNA) coiled together to make a double helix |
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What instructions do DNA molecules have? |
How the organism should be constructed and how each cell should function |
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What do genes control? |
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? |
Structural proteins (cell growth and repair) or functional proteins (speed up chemical reactions) |
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Chromosomes usually come in... |
Pairs |
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How many pairs of chromosomes do human cells have? |
23 pairs of chromosomes (46 in total) |
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How many chromosomes do the sperm/egg cell contain? |
23 single chromosomes |
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A gene can have different versions called... |
Alleles |
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For each gene, how many alleles do you inherit? |
One from your mother and one from your father. |
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What are two alleles that are the same called? |
Homozygous |
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What are two alleles that are different called? |
Heterozygous |
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What is the combination of alleles you have called? |
Your genotype |
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What is the phenotype? |
The characteristics you actually show |
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What's a dominant allele? |
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? |
The recessive allele controls the development of a characteristic only if a dominant allele isn't present |
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XX represents? |
Female |
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XY represents? |
Male |
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What's the name on the gene that determines the sex of the individual? |
The sex-determining region Y (SRY) gene |
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What does Huntington's Disorder affect? |
The central nervous system |
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How is HD caused? |
It's caused by a faulty allele on the fourth pair of chromosomes |
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What does Cystic Fibrosis affect? |
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 CF? (4) |
Weight loss, difficulty in breathing, chest infections and difficulty in digesting food |
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What is meant by a carrier of a genetic disease? |
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? |
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? |
When the fetus actually has the disorder |
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What's a true negative? |
When the fetus doesn't have the disorder |
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What's a false positive? |
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? |
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? |
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? |
Reproduction without the fusion on gametes (sex cells) |
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How are animal clones produced artificially? |
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? |
The new plants/individual will be susceptible to the same diseases as the parent |
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What are embryonic stem cells? |
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? |
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? |
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? |
They're taken from areas that are adapted for the replacement and repair of tissues, such as the umbilical cord |
