All Flashcards
(21 cards)
Describe the stages of embryonic development
Starts as 8 identical cells - zygote
5 days after conception - blastocyst forms
Then outer blastocyst cell layer forms placenta
Inner cell mass of 50 cells form the embryo tissue - pluripotent stem cells
What is a human zygote
8 identical cells, all totipotent
What is a blastocyst
Hollow ball of cells that forms after 5 days of conception
What are totipotent cells
Total potential so can develop into a human and all cell types
What are pluripotent cells
Potentially give rise to most cell types not all
What are multi-potent cells
Adult stem cells
Give rise to some cell types
What is the hardy Weinburg equation
P squared + 2pq + q squared = 1
Freq of homozygous dominant PLUS freq of heterozygous individuals PLUS freq of homo recessive individuals
What is hardy weinburg used for
Used to see change in allele freq over time
What are P and Q in hardy W
Dominant = P
Recessive = Q
10 stages of fertilisation
1- sperm reach ovum
2- chemicals released, triggers acrosome reaction
3- acrosome swells, fuses with sperm cell membrane
4- digestive enzymes released from acrosome
5- enzymes digest through follicle cells
6- enzymes go through zona pelucida
7- sperm fuses with ovum membrane
8- sperm nucleus enters ovum
9- enzymes released from lysosomes in ovum, thicken jelly like later
10- nuclei of the ovum and spent fuse
6 parts of sperm
Acrosome Head Middle Flagellum Motiochondrion Nucleus
7 parts of ovum
Cytoplasm Haploid nucleus Lysosomes Follicle cells Zona pellucid Lipid droplets Cell surface membrane
What is sex linkage
Characteristics become sex liked when the locus of the allele that code for it is on a sex chromosome
How are T cells activated
6 stages
Bacteria with antigens in surface enter the body
Macrophage engulfs
M presents the antigens and becomes antigen presenting cell
T helper cells with complementary receptors (CD4) binds to antigens
T helper activated and divides
Created clones of T memory and helper
Quicker response
What are T cells
Type of lymphocyte
Specific immune response
T helper - stimulates. Cells which make antibodies and enclave phagocytes
T killer - destroys foreign antigens
2 stages of photo synthesis
What they use and make
Where
Light dependent 1st stage
Used light energy and H20
Makes reduced NADP and ATP and waste product of O
Thylakoid
Independent Uses reduced NADP and ATP makes C6H12O6 Reduced CO2 into carbohydrates Stroma
Light dependent stage
6 stages
- Light energy raises 2 electrons in each chlorophyll molecule- excited state
- Elections leave, travel on electron carries molecules forming electron transport chain
- Electrons from PS2 pass from carries = losing energy. Energy is used phosphorylation for ATP
- Electrons from PS2 replace PS1
- Enzyme catalysed photolysis( O2,hydrogen ions + electrons)
- Electrons from PS1 combine with co - enzyme NADP + hydrogen ions from water = reduced NADP
Stages of speciation
Reproductive isolation usually from geographical but can be temporal, behavioural, habitat
Prevents interbreeding
Less similar different selection pressures
Random Mutations
Different alleles
Can’t successfully interbreed
No fertile offspring
Define gene pool
All the alleles of all the bees present in a population
Allele freq equation
P+q=1
P is dominant
Q is recessive
Only used with 2 alleles for one gene
What is the structure of collagen
It’s a fibrous protein so it’s stick teal and insoluble
3 polypeptide chains held together by hydrogen bonds
With cross links for extra strength
