B1 you and your genes

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  • Created by: 1i22y
  • Created on: 05-04-16 12:30
how do genes carry the instructions that control how you develop and function?
they tell the cells to make proteins needed for your body to work.
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how are nuclei chromosomes DNA and genes connected?
the nucleus contains chromosomes, these contain very long molecules of DNA. A gene is a section of DNA that has the genetic code for making a certain protein
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what do functional proteins do?
take part in chemical reactions and allow the body to function. E.g. enzymes such as amylase
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what do structural proteins do?
build the body and give it structure, rigidity and strength. E.g. collagen in ligaments and keratin in skin
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some characteristics are controlled by several genes working together. what do these characteristics show?
these characteristics will show continuous variation across a population (e.g. eye colour and height)
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what is a genotype?
a persons genetic make-up - your genes. The genotype of an organism demonstrates the alleles present for a particular characteristic
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what is your phenotype?
a persons observable features - the phenotype depends on your genes and the environment
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why do identical twins have identical genotypes?
because they develop after a fertilised egg splits into two (it has already been fertilised)
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how many chromosomes does a human cell contain?
46
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how many chromosomes does a sex cell contain?
23 - it fertilises with another sex cell to form 46
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what happens when an egg and sperm cell fertilise?
it forms a zygote, the cell contains 46 chromosomes. one chromosome in each pair comes from the mother, the other from the farther
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what is a characteristic of a pair of chromosomes?
a pair of chromosomes carry the same genes in the same place, on each chromosome within a pair. HOWEVER there are different versions of a gene called alleles
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what does homozygous mean?
both the alleles for a gene are the same
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what does heterozygous mean?
both the alleles for a gene are different
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why are brothers and sisters not identical?
because they inherit different combinations of alleles from their parents
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how do you determine whether you inherit something or not?
if you inherit 1 or 2 dominant alleles you have the characteristic. if you inherit two recessive you don't have the chracteristic
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what does the 23rd chromosome do?
determines or sex. females have two XX chromosomes, males have an X and a Y. the chromosomes in sex cells are not in pairs. every egg has an X chromosome and half the sperm has an X and the other Y
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what are long chromosomes and short chromosomes?
long chromosome is X. short is Y
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what is the Y chromosome?
a sex-determining gene. this makes an embryo develop testes, and so become male. when there is no Y chromosome, the embryo develops ovaries
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what is Huntingdon's Disease? how is it caused?
caused by a one faulty dominant allele. a person can get it from just one person.
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what is Cystic Fibrosis? how is it caused?
happens in children - makes a thick sticky mucus. caused by a faulty recessive allele. a child who has two faulty alleles - one from each parent has the disease. a child with one faulty allele is a carrier.
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what are the symptoms of Huntingdon's Disease?
tremor and clumsiness, memory loss and concentration problems and mood changes. symptoms develop after the age of 35
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what are the symptoms of Cystic Fibrosis?
difficulty breathing and digesting food and causes frequent chest infections (because of mucus)
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what is a genetic test?
Genetic testing can be used to find out whether a person is carrying a specific genetic mutation (altered gene) that causes a particular medical condition.
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genetic testing during pregnancy may involve cell sampling what is cell sampling?
when cells from the developing foetus can be collected so that the genes can be examined for a disease
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a way in which foetal cells are collected in cell sampling is amniocentesis test. what is this? and what are the risks?
when you collect cells from the foetus which are present in amniotic fluid. RISKS: 1% chance of miscarriage, results not 100% reliable and there is a small risk of infection
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a way in which foetal cells are collected in cell sampling is chorionic villus test. what is this? and what are the risks?
testing a sample of cells from the placenta. RISKS: 1% chance of miscarriage, results not 100% reliable and there is a small risk of infection
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what is IVF?
fertility drugs are taken by the female so that several eggs are released and collected by a doctor. These eggs are then fertilised in a Petri dish by sperm, either from the father or a donor.
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what is PDG (pre-implantation genetic diagnosis)?
after IVF has taken place PDG can then take place. Once the embryos have reached the eight-cell stage, one cell is removed from each. The cells are tested for the allele posing a risk (for example the Huntington’s allele). This is known as PGD. Embry
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what is a false negative?
when the test result says that a person does not have a disease, but they do
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what is a false positive?
when the test result says that a person does have a disease, when they don't
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what is asexual reproduction?
when only one parent is involved - so the offspring has identical DNA to the parent
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how can plants asexually reproduce?
using runner (e.g. strawberries) and producing bulbs (daffodils)
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what are the advantages of producing clones?
successful characteristics seen in offspring and it is useful when plants/animals live alone
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what are the disadvantages of cloning?
no genetic variation (this means that if a disease broke out then the population would be wiped out
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what are the steps to making an artificial clone?
remove an egg cell nucleus (now an 'empty' cell) then take a nucleus from an adult body cell of the organism you want to clone and transfer it to the 'empty' egg cell. then grow the embryo for a few days and implant into the uterus
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what are the two types of stem cells?
adult stem cells - these are unspecialised cells that can develop into many (but not all) types of cells embryonic stem cells - these are unspecialised cells that can develop into any type of cell
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During the development of an embryo, most of the cells become specialised. what does specialised mean?
(cells with modifications to structure according to the task they have to perform). They cannot later change to become a different type of cell.
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what could stem cells be used for?
making new brain cells to treat people with Parkinson’s disease, rebuilding bones and cartilage, repairing damaged immune systems and making replacement heart valves
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what do embryos contain and what does it do?
But embryos contain a special type of cell called stem cells. These embryonic stem cells can grow into any type of cell found in the body so they are not specialised
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Card 2

Front

how are nuclei chromosomes DNA and genes connected?

Back

the nucleus contains chromosomes, these contain very long molecules of DNA. A gene is a section of DNA that has the genetic code for making a certain protein

Card 3

Front

what do functional proteins do?

Back

Preview of the front of card 3

Card 4

Front

what do structural proteins do?

Back

Preview of the front of card 4

Card 5

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some characteristics are controlled by several genes working together. what do these characteristics show?

Back

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