biology
- Created by: rebecca heather
- Created on: 19-10-15 17:46
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- biology
- genes chromosome and DNA
- genes are instructions for cells 1)each genes is a code for making a certain protein 2)other proteins are functional proteins
- an organisms genotype describes the genes its got 1) an organisms genotype is all of the genes it has 2) some characteristics are controlled only by genes 3) other characteristics are controlled by environmentalfactors 4)there are also characteristics controlled by both genes and environmentalfactors e.g weight
- genes and variation
- children resemble both parents ,but are identical to neither
- 1) children get some of their alleles from each of their parents.
- 2)this is why children look a bit like both of their parents
- 3)but they won't exactly be the same as their parents because they haven't got all the same alleles-some came from the other parent
- 4) every child will have a unique combination of alleles-no one looks the same apart from twins
- sperm and egg cells have half of the normal amount of DNA
- 1) The sex cells are different from ordinary body cells because they contain just 23 single chromosome.
- 2) when the sperm fertilizes the egg ,the 23 chromosomes in the sperm combine with the 23 chromosomes in the egg
- 3)the fertilized egg then has 23 pairs of chromosomes like an ordinary body cell.
- 4)the two chromosomes in a pair always carry the same genes and each gene is always found in the same place on the two chromosomes.alleles are different versions of the same gene
- 3)the fertilized egg then has 23 pairs of chromosomes like an ordinary body cell.
- 2) when the sperm fertilizes the egg ,the 23 chromosomes in the sperm combine with the 23 chromosomes in the egg
- genes and variation
- children resemble both parents ,but are identical to neither
- 1) children get some of their alleles from each of their parents.
- 2)this is why children look a bit like both of their parents
- 3)but they won't exactly be the same as their parents because they haven't got all the same alleles-some came from the other parent
- 4) every child will have a unique combination of alleles-no one looks the same apart from twins
- sperm and egg cells have half of the normal amount of DNA
- 1) The sex cells are different from ordinary body cells because they contain just 23 single chromosome.
- 2) when the sperm fertilizes the egg ,the 23 chromosomes in the sperm combine with the 23 chromosomes in the egg
- 3)the fertilized egg then has 23 pairs of chromosomes like an ordinary body cell.
- 4)the two chromosomes in a pair always carry the same genes and each gene is always found in the same place on the two chromosomes.alleles are different versions of the same gene
- 3)the fertilized egg then has 23 pairs of chromosomes like an ordinary body cell.
- 2) when the sperm fertilizes the egg ,the 23 chromosomes in the sperm combine with the 23 chromosomes in the egg
- 1) The sex cells are different from ordinary body cells because they contain just 23 single chromosome.
- genes are shuffled together randomly to make eggs and sperm
- when people produce sperm or egg cells,their pairs of chromosomes separate and go into different cells
- children resemble both parents ,but are identical to neither
- 1) The sex cells are different from ordinary body cells because they contain just 23 single chromosome.
- genes are shuffled together randomly to make eggs and sperm
- when people produce sperm or egg cells,their pairs of chromosomes separate and go into different cells
- children resemble both parents ,but are identical to neither
- inheritance and genetic diagrams
- the combination of alleles determines the phenotype
- 1) alleles are different versions of the same gene
- if your homozygous for a trait,you have two alleles the same for that particular gene if your heterozygous for a trait,you have two different alleles for that particular gene.
- 4)alleles can be dominant or recessive.if you have two dominant alleles for a gene or one dominant and one recessive allele,only the characteristic thats caused by the dominant allele will be shown
- 5)to show the characteristic thats caused but he recessive allele,both alleles for a gene have to be recessive.
- 2)most of the time you have two of each gene one from each parent
- 6)in genetic diagrams,letters are used to represent alleles.alleles that produce dominant characteristics are always shown with a capital letter,and alleles that produce recessive characteristics with a small letter.
- the combination of alleles determines the phenotype
- genetic diagrams and sex chromosomes
- your chromosomes decide whether your male or female
- all men have an X and Y chromosome XY-the Y chromosome causes male characteristics. all women have two chromosomes **-the lack of Y chromosomes causes female characteristics
- your chromosomes decide whether your male or female
- genetic disorders
- 1)some genetic disorders are inherited-one or both parents carry a faulty allele and pass it on to their children.
- cystic fibrosis and hunting tons disease are both caused by a faulty allele of a single gene.
- symptoms of huntingtons disease is shaking,clumsiness ,memory loss,mood changes and poor concentration
- symptoms of cystic fibrosis is thick sticky mucus in the air passages,gut and pancreas,breathing difficulty,chest infections and difficulty in digesting food.
- cystic fibrosis and hunting tons disease are both caused by a faulty allele of a single gene.
- 1)some genetic disorders are inherited-one or both parents carry a faulty allele and pass it on to their children.
- clones
- asexual reproduction
- this means that there is only one parent,and the offspring are genetically identical to each other and the parent.
- clones are genetically identical organisms
- sexual reproduction produces offspring that are genetically different.any differences will be due to environment.
- animal clones
- the nucleus of an egg is removed leaving no genetic information then the nucleus from an adult diner cell is inserted in its place.the cell is then stimulated so that it starts dividing and the embryo produced is genetically identical to the doner cell
- asexual reproduction
- stem cells
- embryonic stem cells
- these are unspecialised stem cells found in early embryos
- they are then removed and the embryo is destroyed.
- embryonic stem cells
- genes chromosome and DNA
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