Biology B1
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- Created by: lena1234
- Created on: 10-05-17 19:06
What is a chromosome?
A long, coiled up molecule of DNA
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How many chromosomes are in a human cell nucleus?
46 (23 pairs)
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What is a gene? What is an allele?
A gene is a short length of a chromosome that codes for one protein. Alleles are different versions of a gene.
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What are the two types of proteins, and what are some examples?
Structural proteins (eg Collagen, which is found in tendons, bone and cartilage) and functional proteins (eg Amylase, a digestive enzyme that breaks down starch to maltose)
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What is the difference between genotype and phenotype?
Genotype is what genes an organism has, phenotype is the characteristics an organism displays
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Why are children not identical to their parents?
Because each child is a unique combination of alleles from both parents
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Why are the sex cells produced by one person genetically different?
Because the chromosomes have different alleles, and 8 million different combinations can be produced from the separation of 23 pairs of chromosomes.
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What is the difference between homozygous and heterozygous?
If you homozygous for a trait, you have two alleles the same for a particular gene. If you're heterozygous, the alleles are different.
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How does an embryo develop into a male?
The Y chromosome contains a gene that codes for the protein that causes testes to develop. The testes produce male sex hormones which cause the rest of the male reproductive system to develop.
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Is cystic fibrosis recessive or dominant? What about Huntington's disease?
Cystic fibrosis is recessive, Huntington's is dominant.
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What are the symptoms of cystic fibrosis?
Breathing difficulty, chest infections, difficulty digesting food, and thick sticky mucus in air passages (and gut and pancreas)
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What are the symptoms of Huntington's disease?
Tremors, clumsiness, memory loss, mood changes, poor concentration
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What is IVF (pre-implantation genetic diagnosis) ?
Embryos are tested for genetic disorders that may have been inherited from a parent, and only healthy ones are implanted. Ones with disorders are discarded.
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Why might children be genetically tested?
To see if they carry alleles for a genetic disorder, to see how a drug will affect them
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Are the results of genetic testing always accurate? Why is this an issue?
No, it can be a false positive or false negative. People might make decisions based on incorrect information.
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Are tests carried out during pregnancy safe?
No, doing a genetic test on the fluid around around a fetus can lead to a miscarriage 0.5-1% of the time
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What are some issues with genetic testing?
Is it fair to put someone under pressure not to have a child, is it right to terminate the pregnancy, might lead to discrimination, insurance companies might refuse life insurance
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What is a clone? What causes differences between clones?
A genetically identical organism, environmental things.
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What organisms can reproduce asexually? How?
Bacteria divide in two, green flies can lay eggs of genetically identical females, plants produce horizontal stems (runners) which produce clones at the tips (eg strawberries), or underground fleshy structures (eg garlic)
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How do identical clones develop?
An embryo splits in two, and two separate, genetically identical babies develop.
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How do scientists make animal clones?
A nucleus is removed from an egg cell, and a nucleus from a donor body cell replaces it. The cell is stimulated to start reproducing, and the organism it develops into is identical to the donor cell.
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What are the two types of stem cells? What are the differences?
Embryonic stem cells (can specialise into any type of cell, kills embryo to remove) & Adult stem cells (maintain & repair old and damaged tissues, can specialise into most types of cells, can be safely removed from bone marrow)
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What does medicine use adult stem cells for?
Blood diseases (eg sickle cell anaemia). Through bone marrow transplants containing stem cells, new blood cells replace faulty ones
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What could embryonic stem cells be used for?
Beating heart cells for people with heart disease, insulin-producing cells for people with diabetes, nerve cells for paralysed people
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Other cards in this set
Card 2
Front
How many chromosomes are in a human cell nucleus?
Back
46 (23 pairs)
Card 3
Front
What is a gene? What is an allele?
Back
Card 4
Front
What are the two types of proteins, and what are some examples?
Back
Card 5
Front
What is the difference between genotype and phenotype?
Back
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