Biology OCR, B1

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What are the instructions to control an organism?
the genes, which are found in the nucleus
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What are genes?
sections of very long DNA molecules that make up chromosomes in the nuclei of cells
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What do genes consist of?
molecular instructions for a cell that describe how to make proteins
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What types of proteins are there?
structural proteins and functional proteins
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What are you characteristics determined by?
genetic factors and environmental factors
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What do chromosomes come in?
pairs
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What do sex cells only contain?
one chromosome from each pair, single chromosomes
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What is an allele?
different versions of a gene. An allele is either dominant or recessive
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How many alleles does an individual have for each gene?
two alleles
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What are the two names for two alleles within a gene?
homozygous (both alleles are the same) and heterozygous (alleles are different from one another)
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Why do offspring have similarities to their parents?
they have a combination of maternal and paternal alleles in the fertilised egg
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Why do different offspring from the same parents differ from each other?
they inherit a different combination of maternal and paternal alleles
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What sex chromosomes do males have?
XY chromosomes
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What sex chromosomes do females have?
XX chromosomes
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what triggers the development of testes?
the sex-determining gene on the Y chromosome. The absence of a Y chromosome allows ovaries to develop
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What is your genotype?
the combination of alleles that an organism has
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What is your phenotype?
the characteristics that the organism displays
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What causes Huntington's disease and cystic fibrosis?
faulty alleles of a single gene
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What disorder is caused by dominant alleles?
Huntington's disorder
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What disorder is caused by recessive alleles?
cystic fibrosis
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What are uses for genetic testing on adults?
can see if an adults possesses a disease-causing allele in their cells
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What are uses for genetic testing on children?
can see if a child has any disease-causing genes, so that possible preventative measures can be taken. Tests can also be carried out before prescribing certain drugs
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What are implications for genetic testing?
risk of miscarriage, results may not be accurate, whether to have children, whether to terminate a pregnancy and whether other family members should be informed
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Implications for testing embryos?
some believe it is unnatural, pre-selection could reduce variation,
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Implications of storing genetic information?
confidentiality problems. Should employers or insurance companies have access to this information? Could cause discrimination
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How can bacteria, plants and some animals produce clones?
reproducing asexually
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What may cause differences between clones?
environmental factors
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How do some clones of plants occur naturally?
plants produce bulbs (e.g daffodils) and runners (e.g strawberry plants)
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How do clones of animals occur?
can occur naturally when cells of an embryo separate (identical twins) and artificially, when the nucleus from an adult body cell is transferred to an empty unfertilised egg cell
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What are the different types of stem cells?
adult stem cells and embryonic stem cells
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What are adult stem cells?
unspecialised cells that can develop into many, but not all types of cells
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What are embryonic stem cells?
unspecialised cells that can develop into any type of cell
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Why is it important that stem cells are unspecialised?
they offer the potential to treat some illnesses
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When do the majority of cells become specialised in multicellular organisms?
the early development of an organism
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Card 2

Front

What are genes?

Back

sections of very long DNA molecules that make up chromosomes in the nuclei of cells

Card 3

Front

What do genes consist of?

Back

Preview of the front of card 3

Card 4

Front

What types of proteins are there?

Back

Preview of the front of card 4

Card 5

Front

What are you characteristics determined by?

Back

Preview of the front of card 5
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