B1

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  • Created by: ShakeraB
  • Created on: 31-12-14 13:46
How many chromosomes are in the human cell nucleus?
23 pairs
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Genes
Instructions for cells to make protein
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Alleles
Different versions of the same gene
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Genotype
All the genes an organism has
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Phenotype
The characteristics an organism dislpays
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What controls an organisms characteristics?
Genes and environmental factors
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How are sex cells different from body cells?
Sex cells have 23 SINGLE chromosomes
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How do children resemble both parents but never seem to be identical to either?
Children get some alleles from each parent so they won't look exactly like their parents as they haven't got all the same alleles.
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Are two chromosomes in a pair ever identical?
No because they have different alleles
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Homozygous
Two alleles that are same for that particular gene
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Heterozygous
To alleles that are different for that particular gene
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Alleles can be dominant or recessive
Two dominant alleles or one dominant and one recessive allele means only the characteristics caused by the dominant allele will be shown
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How do characteristics for recessive alleles show?
When both alleles for gene are recessive
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Genetic diagrams
Used to work out how characteristics from one generation move to the next
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Punnet square
Another way to work out a genetic cross
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What sex chromosomes do human males have?
All males have XY chromosomes, the Y chromosomes causes the male characteristics
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What sex chromosomes do human females have?
All women have ** chromosomes, the lack of Y chromosomes causes the female characteristics
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How does a gene on one of the human sex chromosomes cause embryos to develop into males?
The gene that makes an embryo into a male causes a specific protein to be produced. This protein causes the development of testes, which produce male hormones.
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Is the allele for cystic fibrosis dominant or recessive?
Recessive, so people with only one copy of the allele won't show symtoms - they're known as carriers
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What are the symptoms for cystic fibrosis?
Thick sticky mucus in air passages, gut and pancreas; Breathing difficulty; Chest infections; Difficulty in digesting food
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Is the allele for Huntington's disease recessive or dominant?
Dominant
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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 chance of a child inheriting Huntington's disease if one of their parents has one copy of the faulty allele?
50%
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During IVF treatment, what is the process of testing embryos to see if they have a genetic disorder called?
Pre-implantation genetic diagnosis
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Other than testing embryos during IVF, give one other use of genetic testing.
To show if a certain drug can be prescribed to them and how effective it could be
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Describe three issues surrounding genetic testing.
The results may not be 100% accurate, so people are told a false negative result or a false positive result. Tests carried out during pregnancy aren't 100% safe. If a test carried during pregnancy is positive, is it right to terminate the pregnancy?
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Clone
A genetically identical organism
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Asexual reproduction
Only one parent and offspring are genetically identical to each other and parent
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How do bacteria reproduce asexually?
Dividing into two so they multiply very quickly
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How do some plants reproduce asexually?
Some produce horizontal stems called runners that move out from base of plant and form clones at their tips, e.g. strawberry plants
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How are identical twins formed?
Single egg is fertilised by a sperm and embryo begins to develop as normal. When the embryo splits into two, two seperate embryos begin to develop. The two embryos are genetically identical
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What are stem cells?
Unspecialised cells that can develop into different types of cells
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Embryonic stem cells
Found in early embryos. Removed from embryo then embryo is destroyed. Have potential to turn into ANY kind of cell.
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Adult stem cells
Found in adult animals. Involved in maintaining and repairing old and damaged tissues, can specialise into many cell types. Safely removed by extracting their bone marrow - no embryos are destroyed
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Describe one way stem cells can be used to cure illnesses
Adult stem cells can be used to treat some blood diseases by bone marrow transplants. Bone marrow contains adult stem cells that can turn into new blood cells to replace the faulty old ones.
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Other cards in this set

Card 2

Front

Genes

Back

Instructions for cells to make protein

Card 3

Front

Alleles

Back

Preview of the front of card 3

Card 4

Front

Genotype

Back

Preview of the front of card 4

Card 5

Front

Phenotype

Back

Preview of the front of card 5
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