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Biology 1 ocr 21st century
Description
OCR 21st century core science, higher, B1
No tags specified
gcse
biology
ocr gcse
gcse ocr
module 1
ocr 21st century
Mind Map by
Aisha_
, updated more than 1 year ago
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Created by
anna.mat1997
over 9 years ago
Copied by
Aisha_
over 9 years ago
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Resource summary
Biology 1 ocr 21st century
Genes, Chromosomes and DNA
1. Most cells have a nucleus containing your genetic material
2. Genetic material in the nucleus is arranged into chromosomes of which there are 23 pairs
3. Each chromosome is one long molecule of DNA that is coiled up
4. A gene is a short length of a chromosome
5. Genes control he development of different characteristics
6. Genes exist in different versions called alleles
Genotype- the genes an organism has
Genes and Variation
Sperm and egg cells have half the normal amount of DNA
Children resemble both parents but are identical to neither
Genes are shuffled together randomly to make eggs and sperm
Half chromosomes are from each parent
Inheritance and Genetic Diagrams
Combination of alleles controls phenotype
Homozygous- two same alleles of a gene
Heterozygous- two different alleles of a gene
Alleles can be dominant or recessive
Sex Chromasomes
Control whether you are male or female
Men have XY
Women have XX
Determined by one gene
Control which hormones and sex organs are produced
Y causes protein to be formed- not formed in women
Genetic Disorders
Caused by faulty alleles
One or both parents carry a faulty allele
Huntingtons
Dominant allele
Tremors
Clumsiness
Memory loss
Mood changes
Poor concentration
Symptoms appear after 40
Cystic fibrosis
Thick sticky mucus
Breathing difficulty
Chest infections (painful coughing)
Difficulty digesting food
Recessive allele
Genetic Testing
Used on embryos children and adults
Embryos
Produced in IVF- check for genetic disorders (pre-implantation genetic testing)
Not 100% safe
Miscarriage
Cause people to terminate?
Children and adults
Checked if they carry alleles for genetic disorders so they can see if their child would inherit a disorder
Tested before drugs are prescribed to see how it will affect an individual
If one member of the family is tested should others?
False positive / false negative
If results become available there could be discrimination
Harder to get a job
More expensive insurance
Clones
Genetically identical organisms
Nature makes clones
Asexual reproduction
Bacteria- divide in two
Plants
Strawberry plants grow new runners
Garlic grow underground fleshy structures (bulbs)
Embryo cells split
Identical twins
Single egg fertilized by a single sperm
Embryo splits in 2
Clone in a lab
1. Nucleus is removed from an egg cell leaving an egg
2. nucleus from adult donor inserted in its place
3. Cell stimulated and divides as normal
Stem Cells
Most cells in the body are specialised
Embryonic stem cells
Unspecialised and found in early embryos
Removed from the embryo then the embryo is destroyed
Potential to turn into ANY cell
Adult Stem Cells
Unspecialised
Involved in maintaining and repairing old and damages tissues
Can specialise into MANY (not all) cell types
Safely removed via bone marrow
Uses
Cure Sickle cell anaemia- bone marrow transplants
Replace faulty cells in the sick
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