Genes to ecosystems tri 1 lect 3
- Created by: Loz1669
- Created on: 28-12-19 17:58
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- Genes to ecosystems
- Human and animal development
- Genetic info is carried on chromosomes
- 46 chromosomes in 23 pairs (22 homologous pairs) ((identical pairs))
- Structure of chromosomes
- DNA: double helix/ proteins form the scaffold for the chromosomes/chromosomes need to be tightly packed into the cell.
- Diploid and Haploid
- Most organisms are diploid meaning they have 2 copies of each chromosome
- Some plants and protozoa are haploid.
- Some organisms are polyploid meaning that they have more than 2 copies
- Organisms tend to have haploid and diploid stages e.g haploid stages in mammals are gametes
- In order to have haploid stages there is a requirement for both mitosis and meiosis cell division
- Organisms tend to have haploid and diploid stages e.g haploid stages in mammals are gametes
- Mendelian Inheritance
- R and r are alleles - these are alternatives of the same gene. As an organism is diploid there are two alleles at the same gene locus. These can either be the same or different.
- Alleles can either be dominant (produce the phenotype) or recessive
- Co dominant genes - neither allele is dominant and both contribute to the phenotype
- Alleles can either be dominant (produce the phenotype) or recessive
- Sex-linked genetics
- Genes are carries on the Y or X chromosome and the genetics are different to autosomal genetics
- X chromosome inactivation
- Females have two copies of X chromosomes but one is always switched off or inactivated
- Multigene genetics
- Genetic recombination can occur which reassorts the genetic material
- Genetic maps can be constructed by measuring recombination
- Genetic recombination can occur which reassorts the genetic material
- Polygenic traits
- Most phenotypes of organisms are based on many genes. When many genes are involved this is known as polygenetic traits
- Genetic Disorders
- 2 Types:
- Inherited
- Chromosome aberrations - defects in chromosome segregation
- 2 Types:
- R and r are alleles - these are alternatives of the same gene. As an organism is diploid there are two alleles at the same gene locus. These can either be the same or different.
- Development of the embryo
- Fertilisation and genetics produce the diploidy zygote which is a single cell. This single cell has no polarity
- A process occurs which causes this to grow into the complex adult form. This process is driven by the information contained in the DNA.
- 1st Stage in the development is the clevage of the single cell zygote into the first two cells... then 4... then 8...
- This solid ball is called MORULA. This cells continues to divide up to the 32 cells stage, the cells can form any part of the new embryo. At this stage the cells are known as stem cells.
- Cells then begin to differentiate after which each cell will ultimately end up specialising as a cell type.
- Part of embryo development is the development of the spinal cord. Failure of the correct closing of the neural tube can cause: spin bifid occulta / cystica and cranium bifida
- Organogenesis is the formation of organs.
- Cells then begin to differentiate after which each cell will ultimately end up specialising as a cell type.
- This solid ball is called MORULA. This cells continues to divide up to the 32 cells stage, the cells can form any part of the new embryo. At this stage the cells are known as stem cells.
- 1st Stage in the development is the clevage of the single cell zygote into the first two cells... then 4... then 8...
- A process occurs which causes this to grow into the complex adult form. This process is driven by the information contained in the DNA.
- Fertilisation and genetics produce the diploidy zygote which is a single cell. This single cell has no polarity
- Nature vs Nurture
- Constant environment
- We place two genetically distinct organisms in the same environment and see whether they behave the same or differently. Can be done easily with plants where we can grow them in the same conditions.
- Constant Genetics
- We compare genetically identical individuals i.e identical twins.
- Constant environment
- Human and animal development
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