2 cells and control Flashcards
what are the stages of the cell cycle for mitosis?
and what happens at eac stage?
- interphase: this takes place between each cell division, the cell has to grow and increae its number of subcellular structures, then eventually doubles each chromosome, starting mitosis
- prophase: the nucleus’ membrane breaks down and the chromosomes lie free in the cytoplasm
- metaphase: the chromosomes line up in the centre of the cell and cell fibres form
- anaphase: the cell fibres attach to the chromosomes and pull one copy of each to either side of the cell
- telophase: a nucleus membrane forms around each cluster of chromosomes
- cytokinesis: the cell membrane closes up, seperatinf the 2 nuclei and splitting the cell in 2
what are the 3 uses of mitosis?
growth of an organism
thr rapair of an organsim
asexual reproduction
why do some organisms rely on asexual reproduction?
only one organism is required, so can reproduce qhenever the conditions are favourable
asexual reproduction is alot faster and organisms such as bacteriause it to quickly colonise new areas rapidly
why does mitosis produce genetically identical diploid cells?
mitosis makes a copy of each chromosome exactly, which is used in the new cell and so each cell has exactly identical chromosomes and the same amount
how does cancer form?
cancer forms as a result of a mutation which causes rapid reproduction of a type of cell, so that cell rapidly reproduces and a lu,p of rapidly dividing cells grows
what is growth in animals?
growth in animals is an increase in cell number and size
why is cell differentiation important in the development of specialised cells?
specialised cells are able to form because some chromosomes or parts of chromosomes are turned off somehow, which results in the cell appearing and behaving differently
What are the stages of growth in plants?
All plants have meristems
What are the main specialised cells in plants?
Palisade cells: contain lots of chloroplasts, found on the tops of leaves
guard cells: on the bottom of leaves, open and close the stomata allowing gassesin and out for resporation
xylem cells: tube-like cells through which water and nutrients are transported through the plant
Where are stem cells found in humans and plants?
human embryos contsist of embryonic stem cells, which are fully undifferentiated
in adults, partially specialised stem cells can be found in their corresponding tissues, most common is bone marroq stem cells, which can naturally change into different types of blood cells
in plants, stem cells are found in the meristems
what is the function of stem cells?
stem cells are used to help grow and repair injuries, also to become organs when the body is developing from an embryo, to replace damaged cells
what are the differences between embryonic and adult stem cells?
embryonic can turn into any type of cell, as every cell in your body originated as an embryonic stem cell when you where an embryo
adult stem cells are less versitile as they are meant to replace damaged cells for the tissue/organ they are in and cant tuinto any cell, just a few necessay ones
where are stem cells used in medicine?
can be cultured to grow tissue and even limbs (not yet used) for transplants
used in stem cell therapy after radioterapy or chemotherapy to repair surronding cells which where damaged by the procedure
could be used to treat paralysis, fixing nerves in the vertibre
what are the risks of using stem cells
people have ethical issues with where they came from
body might reject them if they’re from a donor
what is the brain made of?
billions of interconnected neurones
what are the main parts of the brain and their functions?
