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32 Cards in this Set
- Front
- Back
How are extracellular enzymes made? (6 marks) |
DNA is transcribed at the nucleus 1)*protein is synthesised at the ribosome (translation) 2) protein from ribosome on RER 3) travels through RER + is processed (adding carbohydrate) & folded (change to 3D shape) 4) protein travels in a vesicle to the GA 5) then through the GA is processed (carbohydrate chains added) & packaged 6) released as a vesicle 7) move to the cell surface (fuses with cell surface membrane) & is secreted as an extracellular enzymes |
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Tissue (& example) |
Similar cells that work together to perform a function E.g. Cardiac muscle tissue |
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Organ (&example) |
Made of various tissues grouped together + work together to perform the a function E.g. heart > muscular, nervous, connective tissue |
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Organ system (&example) |
Many different organs that work together to perform the a function E.g. Circulatory system > heart, arteries, veins, capillaries |
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Mitosis > interphase |
- G1 & G2 = synthesis of organelles & proteins - S = multiplication of chromosomes - organelles replicates so there are spare ones - ATP content is increased > needed for cell division (at the end of the cycle) |
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Mitosis (prophase) |
- DNA condenses - nuclear envelope breaks down - centrioles move to opposite ends of the cells and begin to form spindles - Chromosomes are free floating in the cytoplasm |
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Mitosis (metaphase) |
- chromosomes meet at the Middle of the cell (equator) - attached to the spindles by their centromeres |
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Mitosis (Anaphase) |
- spindles contract & pull chromatids towards opposite poles of the cell - centromere is divided into 2 when sister chromatids split |
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Mitosis (Telophase) |
- chromatids uncoil & becomes long & thin again > become chromosomes - cytokinesis: the cytoplasm splits into 2 - 2 separate nuclei form in 2 separate cells (nuclear envelope forms around each) - daughter cells are genetically identical to the original cell |
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Cortical reaction |
- sperm head (cell membrane) fuses with the egg cell membrane - corticle granules releases when sperm head (cell membrane) touches egg cell membrane - corticle granules thicken the zona pellucida to ensure its impenetrable to other sperm (prevent polyspermy) (ONLY sperm nucleus enters egg cell as flagellum is discarded) |
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Acrosome reaction |
- when the sperm head touches the egg cell (zona pellucida/follicle cells) the acrosome swells (bursts) - digestive enzymes are released which break down the zona pellucida (allowing the sperm to penetrate/ move towards the egg cell membrane) |
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Why is it important that meiosis occurs |
- produces haploid nuclei - combine to create a diploid nuclei |
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Prokaryotes (general points) |
- unicellular organisms/ smaller & simpler - e.g. bacteria - organelles/ ultrastructure is similar |
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Eukaryotes (general points) |
- multicellular/ complex and large - e.g. all animal and plant cells - similar organelles/ ultrastructure |
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What is the role of the acrosome? |
To allow the sperm to penetrate the egg cell |
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What is the purpose of the zona pellucida? |
To protect the egg cell from damage To prevent polyspermy |
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What is fertilisation (definition) |
The fusion of gametes (egg & sperm cell) to form a zygote |
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What does locus mean (in this module)? |
The location of genes on a chromosome |
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Sex Linked genes |
- more likely on males due to one X chromosome - if a female has a faulty/recessive allele for the characteristic on one sex chromosome the other X chromosome is likely to contain a dominant allele to over ride this - sex linked because the alleles for these disorders are on the sex chromosomes |
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How does meiosis ensure genetic variation? |
1)Independent assortment: random combination of chromosomes (so alleles) from both parents > gametes have a possibility of MANY unique combinations 2)Crossing over: some sections of chromosomes are swapped (twist around each other & combine to new chromosome) > unique gene (allele) combinations that are not present in either parent |
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What is the role of mitosis |
- growth (producing new identical cells) - repair (replacing old cells with new identical cells) |
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Pluripotent |
- can differentiate into most cell types - not extra embryonic stem cells e.g. placental cells & umbilical cord cells - some genes inactivated > X turn into these types of cells |
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Totipotency |
- can differentiate into all cell types - including extra embryonic cells e.g. placental & umbilical cord cells - no genes are inactivated |
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How does society influence the use of stem cells |
1. Monitoring (deciding the maximum age of an embryo) 2. Info (giving public& government info) 3. Licensing (checking the source of stem cells) 4. Allowing research (deciding whether research is allowed) 5. Guidlines (laws in stem cell use) |
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How does crossing over happen |
- Homologous pairs line up - exchange of chromosome segments between non-sister chromatids - meiosis > contain combinations of genes dif from their parents -some sections of chromosomes twist around each other, are swapped & combine to new chromosome |
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How does independent assortment happen |
random combination of chromosomes in meiosis |
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How do features of the sperm aid reproduction? (All except acrosome) |
- ATP > energy used for movement of the flagellum - flagellum > ability if sperm to swim (move) |
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Features of the egg cell |
- big lipid droplets > for energy > nutrition for the egg cell - follicle cells > protective coat - zona pellucida > protective layer > stops penetration/ damage - corticle granules > prevent polyspermy |
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What makes extracellular proteins |
Ribosomes on RER |
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Observing mitosis |
• cut off garlic root tip • leave in acetic alcohol, then water, then HCL • macerate the root tip with mounted needle/ mount under a coverslip • stain garlic root tip (orcein ethanoic) • observe mitosis > count no. of visible chromosomes > calculate mitotic index • control - temperature of solution (place in incubator at 25 degrees), source of garlic (same plant) |
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What is the mitotic index |
The proportion of cells undergoing mitosis Mitotic index = no. of cells with visible chromosomes/ total no. of cells |
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What is the difference between an embryo and a zygote |
Zygote is firmed from the fusion of the gametes > embryo formed from zygote (so at a later stage) |