Cell Division Flashcards
where is the genetic material stored in the cell
nucleus
the DNA is arranged in structures call ………………..
chromosomes
what does each chromosome carry
different genes
what are genes
a gene is a specific section of DNA that codes for the production of one specific protein
what do different genes determine
different genes determine the development of specific characteristics
in body (somatic) cells how are chromosomes found in
pairs
how many chromosomes are in a somatic cell
46 chromosomes , 23 pairs
what is it called when the full number of chromosomes are found inside the nucleus of a somatic cell
diploid cell
somatic cells in a multicellular organism must be able to divide + produce new cells so that : (4 reasons)
- damaged + old cells are replaced
- tissues + organs can be repaired
- tissues + organs can grow
- the organism itself can grow
what are the 2 main stages of the cell cycle
- Cell growth + DNA replication
- Mitosis
describe the stages in the cell growth phase
- cells get bigger
- DNA doubles –> forms 2 copies of each chromosome
- sub-cellular structures like ribosomes + mitochondria double
describe the stages of mitosis
- chromosomes line up in the middle / equator of the cell
- half of the chromosomes are pulled to each pole of the cell
- 2 nuclei form within the cell –> nucleus divides
- cytoplasm, organelles + cell membrane + nuclei are split to form 2 new daughter cells which are genetically identical
what type of reproduction is binary fission
asexual reproduction
how is bacteria difference from mitosis
- mitosis is the division of the nucleus BUT bacteria do not have nuclei
- spindle fibres also not formed in binary fission
describe the stages of binary fission
- cell replicates DNA
- increase in size
- divide into 2 genetically identical daughter cells
stem cells is an …………………. cell
undifferentiated
what process do stems cells divide by
mitosis
stems cells differentiate into what
into different types of specialised cells
what are the 3 types of stems cells
- embryonic stem cells
- adult stem cells
- plant stem cells
what is the function of an embryonic stem cell
- stem cells found in early human embryos - can be cloned and made to differentiate into any type of cell = totipotent stem cells
describe the function of a adult stem cell
- found in adult bone marrow
- can form many types of cells –> including blood cells
where is the adult stem cell found
adult bone marrow
where are plant stem cells found
meristems
describe the function of a plant stem cell
- stem cells found in plants in meristems
- Meristematic tissue found in the shoot tips + root tips
- can differentiate into any type of plant cell throughout plants entire life
what are the uses of embryonic stem cells
- insulin-producing cells to treat people with diabetes
- neurones could be used to treat people with spinal cord injuries –> paralysis
advantages of using embryonic stem cells
- therapeutic cloningused to produce ** embryonic stem cells** which have the same genetic info as the patient
- stem cell produced from the embryo would contain ((same genes as patient**
- prevents cells being rejected by patients body –> can be used for medical treatment
risks / disadvantages of embryonic stem cells
- grown artificially in a lab, may become contaminated with viruses –> could be passed onto patient
- ethical or religious objections
uses of adult stem cells
- treat some diseases –> sickle cell anemia:
- stem cell extracted from bone marrow which are used to faulty red blood cells
uses of plant stem cells
- produce clones of whole plants quickly + economically
- Rare species cloned to protect from extinction
- crops with desirable features (e.g. disease resistance) can be cloned to produce large no. of identical plants for farmers
what are the ethical issues for why some people are against the use of stem cells in research
- fell thet human embryos are a potential life
- obtaining stem cells from an embryo destroys the embryo + destroys life
- embryos can’t give consent
- time + money could be spent to fine alternative solutions e.g. find method to turn differentiated adult cell back into stem cell
some people are for the use of stem cells in research because:
- fell that treating + curing existing patients who are suffering is more important than the rights of the embryo
- embryos that are used are usually embryos that would be destroyed as biological waste : extra embryos generated by fertility clinics but are not used
