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Cell division (Division (Use
Repair; Replace
Maintenance; Growth,…
Cell division
Division
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Information (46, 23 pairs)
Chromosomes (nucleus)
Carry thousands of genes
for protein synthesis (PT)
for mitosis (characteristics)
pair - part father, part mother
Genes (instructions)
Section of DNA (unique)
many genes = characteristics
Genes grouped in chromosomes
Gametes only have 23 chromosomes
Mitosis (asexual)
Body - all genes the same
little to no genetic variation
Produce 2 daughter identical cells
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Cell life
< 24 hrs - several years
Baby (Rapid); (fast as old ones die)
Childhood (Fast)
After puberty (Slower)
Still mitosis as an adult
(Hair follicles, skin, blood, digest lining)
Skin divides rapidly (300M/min)
Mitosis slowing leads to ageing
Process
Growth - longest stage, increase mass
Replicate DNA, 2 copies of chromosomes
Increase organelle count (mito, ribo) for divide
Mitosis - Set of chromosomes pulled to ends
of dividing cell, nucleus divides
Cytokinesis - c.membrane, cytoplasm splits
Growth & Differentiation
Zygote = 3.72 x 10^13 cells (life)
Early develop = unspecialised
Cells aren't the same as stem cells
Grow, develop, leads to differentiation
Animal cells
Most cells specialised by birth
Restrict to growth, replace (mature)
Some genes turn on, some genes off
most cells can divide (blood, skin can't)
Cells can only divide into same sort of cell
Adult stem cells replace undividing cells
Replace damaged cells (sometimes)
Nerve cells aren't usually replaced
Once that cell, always that cell
Cloning plants
Identical offspring = cloning
Identical plants from leaf piece
Right condition - unspecialise, mitosis
Most animals differentiate permanently
Clone animals only by clone embryos
Plant cells (redifferentiate)
Able to differentiate through life
indifferent cells in active region
(stems, roots) aka Meristems
mitosis (regular), elongate, differentiate
Differentiate only in final position of plant
Definition :star: :star:
the process by which cells, tissue, and organs acquire specialized features, especially during embryonic development.
Stem cells dilemmas
Adult stem cells
Pros: £1000 to collect many
Adult permission; Safe procedure
Cons: Limited differentiation, Infection
Slow divide (4 hrs); high reject chance
Embryonic stem cells
Pros: Differentiate most types
Fast divide (30 mins); low reject chance
Cons: Ethical issues; £5000 for few
More research needed (rights, religion)
In general
Pros: Differentiation
large numbers grown
treat human diseases
Cons: Expensive
Hard to control, relevant?
Drugs for life (rejection)
Future
found in umbilical cord
found in amniotic fluid (womb)
Try to solve ethical problems
some in tubes (liver - pancreas)
lost by type 1 diabetes
Therapeutic cloning (no reject)
use adult cells to make embryos
own cells turned back to embryonic
Recover:
Spinal cord injuries diabetes
Heart attack damage; blindness
Cartilage, bone damage
Stem
cells
Function
Egg + sperm = zygote - new cell
divides into hollow cell ball (embryo)
Stem cells differ to special cells
Still have adult stem cells (replace)
Bone marrow is a good source
Tiny amounts in each tissue
Using them
1998 - 2 scientists cultured embryonic cells
Used nerve cells for paralysis in rats
2010 trials - human paralysis recovery
2014 trials - eyesight recovery
Soon trials - diabetic, organ, infertile etc
Benefits
Spinal injury = paralysis (nerves can't repair)
Type 1 diabetes need insulin inject
(Pancreas special cells stop working)
Many benefit from damaged body parts replace
Plant stem cells (meristems)
Clone rare plants - cheap, fast
Clone plants for research; agriculture
Horticulture cloning (orchids etc)
Your bananas are cloned