Biology Sac 1 Term 4 Flashcards
What evidence shows reproduction in the fungi
The presence of the Zygospores
What evidence shows the reproduction in the strawberry plant
The runners and the fruit
Mitosis - prophase
Chromosomes condense and move to opposite cell ends
The nuclear membrane breaks down
Centrioles form spindle fibres
Mitosis - metaphase
Centromeres continue to be drawn by the spindle fibres
Metaphase - Anaphase
Spindle fibres contract, pulling the centromeres in different directions.
The centromere splits, separating the two chromatids.
The separated chromatids are then pulled to opposite ends
Mitosis - telophase
Prophase in reverse
Nuclear membrane is formed around the chromosomes at each pole
The spindle fibres are dismantled and disappears
The chromosomes become longer and thinner
G1 phase
Cell gains energy
Undergoes metabolic processes
Cell almost doubles in size
Cell gains multiple organelles
S phase
Synthesis phase
Chromosomes are replicated in the nucleus
G2 phase
Cell undergoes secondary growth
Cell prepares for mitosis by synthesising the materials such as proteins needed for division
What is a centriole and how does it look during mitosis and what does it do during mitosis
A tiny cylinder structure found in eukaryotic cells
Composed of tubulin
The centrioles organise chromosomes and helps the formation of spindle fibres
Haploid
23 (n)
Diploid
46 (2n)
Teraploid
48
Fragmentation
When the body breaks down into multiple organisms
Budding
Division of cytoplasm is unequal and the new individual arises as and outgrowth or bud
Spores
A haploid cell that develop into a new organism without sexual reproduction
Cloning - nuclear transfer
Removing nucleus of an unfertilised egg and replacing nucleus with nucleus of adult somatic cell
The egg is then transplanted back into organism
Issues with cloning
- susceptible to disease ~ less genetic diversity
- high failure rate ~ current cloning technology is highly insufficient
- Adverse health effects ~ animal welfare concern medical problems occur throughout animals life
- premature ageing ~ telomeres of a clone is shorter
- cloning food products is a major concern
Difference between mitosis in eukaryotes and prokaryotes
Eukaryotes have membrane bound organelles so the process of mitosis in prokaryotes is much simpler
What are Mutagens
A physical, chemical or biological agent that caused a mutations in DNA such as cancer
How does apoptosis occur in cells
The cells surface membrane buds to form apoptotic bodies
These contain the remnants of the cytoplasm, organelles and chromatin fragments. Phagocytic cells remove the apoptotic bodies.
What happens if Apoptosis goes wrong?
Then webbing between fingers and toes remains
What is pluripotent
A stem cell that can differentiate into any of the three germ layers
What are the 3 germ layers?
Ectoderm (outermost layer) forms hair, epidermis, PNS, brain and spinal cord cells
Mesodermal (middle layer) forms muscles and cartilage and gonad cells and kidney cells
Endoderm (innermost layer) forms bladder, lungs and digestive system lining (pancreas, colon, liver and stomach
