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  • Created by: katherine
  • Created on: 09-06-13 17:07
Define the term allele
The alternative form of a gene
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Define the therm gene
The section of DNA on a chromasome coding for a particular polypeptide
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Define the term genotype
The genetic make up of an organism, and the alleles the organism contains
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What are the 3 maine charecteristics of genes
They can seperate and combine, They can mutate, They code for th eproduction of specific polypeptides
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What is the name for the gene positon of an allele on homologus chromasomes
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for each locus on a chomorosome, name the 3 possible allele combinations
Heterozygouse, homozygous dominant, homozygous reccesive
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Define the term mustation
A change in the sequence of bases in DNA
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What is monohybrid inheritance
The inheritance of a single pair of contrasting charecters
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What is mendels first law (the law of segregation)
The charecteristics of an organism are determined by factors (alleles) which occur in pairs. Onl yone pair of factors (alleles) can be present in a single gamete
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What is the dihybrid ratio
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What is mendels second law
Either one of a pair of contrasted charecters may combne with either of other pair
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how many pairs of chromasomes do humans have
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what is a female chromasome made up of
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What is a male chromosome made up of
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Allels carrie donly on the x chromasome are describes as_______________?
Sex linked
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The absence of factor 8 results in what
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in which gender does this cndition almost exclusivly occur
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Why is the condition less common in females
it requires a double recessive
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when does recombinatin take place
when alleles are exchanged between homologus chromasomes as a result of crossing over
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define the term mutatoin
a change in the amount, arrangemtn or structure in the dna of an orgnaism
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what kind of mutations can be inherited
mutations that coocur in the form of gametes
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What can mutations provide a source for
of material for natural selcetion pressures and therefor evolution
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What increases rate of mutaton
ionising radiation and mutagenic chemicals
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Give soem examples of mutagens
Xrays, gamma rays, and uv light, chemicals such as polycyclic hydrocarbons in cigarette smoke
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what is the term for a mutagen that causes cancer
a carcinogen
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Mutatoins can happen in 2 ways which are what
DNA is not copied properly before cell division, choromsomes are damaged and break
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Small errorsinvolving only 1 gene in dna replicaittion are reffered to was what
gene or point mutations
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if broken chromasomes dont repaire themselves correctly this can lead to large changes in the structure of DNA, these are called
Chromasome mutatoins
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What are the types of gene mutation
duplication , insertion, deletion, inversion or substitiution
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HOw can amutation cause change ina phenotype
if incorrect sequence of amino acids is produced, protiens eg. enxzymes are nonfuctional ergo they are unable to catalyse a specific reatoin
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Give an example of this
albino organisms lacking enzymes necassary to convert a chemical precursor into melanin
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What type of gene mutation causes sicle cell anemia
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what is the problem with sickle shaped RBC
they can carry less owygen, resulting in anemia and possible death
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the mutant gene is codominant, what is the heterozygous conditoin refered too
sickle cell trait
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when are mutaiton smost likley to occur
during meiosis
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what can mutaiton result in
chomromasmes not being shared evenly between daughter cells
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what is non dysjunction
A process in wihch faulty cell divisoin means that one of the daughter cells recives 2 copies of a chromosome whil the other get none
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Give an example of this
Downes syndrome
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which number chromasome is efecte din downs syndrome
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oocytes with no 21 die, but ones with 2 may be fertilised, the zygote then has 3 chromosome 21s, known as...
Trisomy 21
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an individual with trisomy 21 has how many chromasomes
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What is it called when a mutation affects a whole set of chromasomes
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what is it caused by
a defect in meisos resulting in a gamete reciving 2 sets of chromasomes
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what wil this zygote be when feritlised by a nmormal hapolid gamete
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what is produced if 2 diploid gametes fuse
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how else can tetraploidmy occur after fertilisatoin
if during mitosis 2 sets of chromasomes double but fail to seperate
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WHat is polyploidy common in, and what is it associated with
flowering plants, beificial charecteristics
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Give an example fo a polyploid
tomatoes, wheat
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why ar triploids usually sterile
They cannot form homologus pairs
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Why are mutations important
they increase variation in the polualtion
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benificial mutatoins ae rare, but what tcan they give an organism
selcetive advantage
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what may happen if the mutation is in a body (somatic ) cell
it may cause cancer, e.g exposure to uv light = skin cancer
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What may happen if the mutation is in a gamete
it wil not effect the individual , but the zygote
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mutations are the basis of....
discontinuos variation
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define the term oncogene
a mutated gene that causes cancer
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why is it uncommon for muations to be expressed
most of them are recessive, so they must remaine in the gene pool until 2 ressecive individuals breed
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What are the substances that cause cancer called
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What to carcinogens do
affect DNA in cells resulting in mutatoins
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What happens to mutatoin sin somatic body cells
They are regoncinsed by the immune system and destroyed
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what may the mutation effect
the regulation of cell divisoin
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what is a lump of mutilated cells called
a tumor
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What is the term for a harmless tumor
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What does a malignant tumor do
Ivade other tissues and spread aorund the body
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what are the harmful chemicals in tabacoo smoke
tar, nicotine, carbon monoxide
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where does tar collect
in the lungs as tobacco smoke cools
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what do the carcinogens in tar affect
the dna inthe cells of the alveoli
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wihch chemical in tobbaco smoke contains carcinogens
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what do the carciogens in tobacco smoke do
casued genes that inhibit cell division to mutate leading to uncontrolled cell division
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What genes can lead to lung cancer
oncogenes and mutated suppressor egens
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what percebtage of all cancer deaths in develped ocuntries are due to the carcinogens in the tar of tobacco somke
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Other cards in this set

Card 2


Define the therm gene


The section of DNA on a chromasome coding for a particular polypeptide

Card 3


Define the term genotype


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Card 4


What are the 3 maine charecteristics of genes


Preview of the front of card 4

Card 5


What is the name for the gene positon of an allele on homologus chromasomes


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