B2 Flashcards
What does the nucleus carry?
The chromosomes
What do the chromosomes carry?
Genes
What do the genes contain?
Instructions for making new cells
What is a gene?
Small packet of information that controls the characteristics of your body. Unique molecule that makes up chromosomes.
How many genes do chromosomes carry?
Could carry several hundred or even thousand genes.
How many chromosomes per cell?
- 46 chromosomes, 23 pairs
- 1 from father
- 1 from mother
What is mitosis?
Stage in cell cycle that divides the nucleus to create identicla daughter cells.
Why identical cells are necessary ?
Same genetic material is needed in every cell.
How do asexual production produce offspring?
Mitosis
How long is the cell cycle?
Tim varies can be less than 24 hours or could take several years.
When is the cell cycle the fastest?
Embryonic stage.
Is the cell cycle fast during childhood?
Yes remain fairly rapid during childhood , as they are growing.
What happens to the cell cycle when puberty is over?
Slows down
What happens to the cell cycle when you are an adult ?
Only for repair and replacement , rather than growth.
What cells can get replaced?
Hair follicles , skin , blood , lining of digestive system.
STAGE 1 of the cell cycle , what is it?
Interphase: cell grows in size , DNA and organelles replicate (ribosomes and mitochondria), forms two copies of each chromosome.
STAGE 2 of the cell cycle , what is it ?
Mitosis: replicated chromosomes line up along the centre and get pulled to opposite poles. The nucleus divides.
STAGE 3 of the cell cycle, what is it ?
Cytokinesis: cell membrane and cytoplasm divide to form 2 new identical daughter cells.
Why is the cell cycle important?
For the growth and development of multicellular organisms
How many cells in the body?
37.2 trillion
What is the state of all cells in early development of both animal and plant embryos?
Unspecialised
What is the common name for unspecialised cells?
Stem cells.
What is the state of the majority of cells in an animal by the time a baby is born?
Specialised
Examples of specialised cells ?
- skin cells
- nerve cells
- muscle cells
What is the definition of a specialised cell?
An adapted , differentiated cell with characteristics to perform a particular function.
How does the stem cells population increase?
Divide through mitosis
What cells can not divide?
- skin
- red blood cells
What happens if a cell cannot divide?
Adult stem cells replace them
What are mature animals cells limited to?
Repair and replacement
What happens usually if a nerve cell gets damaged?
It is permanently damaged , and can cause paralysis
What is the difference between animals and plant cells in terms of differentiation?
Plant cells differentiate throughout their lives, animal cells do not
Where are stem cells found on a plant?
The meristem
Where does active transport take place continuously on plants?
Root hair cells
Do plants grow all throughout their lives?
Yes,
Can plant cells redifferentiate?
Yes, they differentiate when in final position , then can redifferentiate at any time
What can you do with a small cell from a plant?
Move it to a different area and it will redifferentiate.
What is cloning?
Producing identical offspring
How you can clone plants?
Take small part of leaf , it will become unspecialised and go through mitosis new cells will differentiate into the xylem , phloem , photosynthesis and root hair cells need to form a new plant.
Why is it difficult to clone animals ?
Animal cells are permanently differentiated.
What is a stem cell?
An undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type , and from which certain other cells can arise from differentiation.
What is a zygote?
The single cell formed when an egg and sperm meet.
Where are adult stem cells commonly found in humans?
Bone marrow
Where are the embryonic stem cells found?
After zygote cell divides into a hollow ball of cells. Inside the that ball are the embryonic stem cells that differentiate to form a specialised cell.
What is the main purpose for adult stem cells?
To stay in tissues for repair and replacement
What are examples of conditions that are down to cells not working and not being able to repair of replace?
- spinal injuries can cause paralysis as spinal nerves can not replace themselves
- type 1 diabetes inject insulin because specialised cells in the pancreas do not work
Why stem cell research is important?
If cells could dedifferentiate, it could save millions of lives.
How plant clones can be made ?
Take stem cells from the meristem .
Why stem cells research is important in plants?
- helps produce large numbers of rare plants
- can also study effects of cloning
- can clone disease resistant plants.
Advantages of embryonic stem cells?
- has potential to develop into any thpe of cell /tissue
- used to treat humans disease
- painless
Disadvantages of embryonic stem cells?
- unethical-embryos cannot give permission
- possible harm/death to embryo
- can transfer viral infection.
Advantages of adult stem cells?
- plentiful supply
- no ethical, issues
- well tried and tested
Disadvantages of adult stem cells?
- painful to extract
- fewer diseases can be treated
- can only form the type of cells as the tissue they were taken from.
What is therapeutic cloning?
An embryo is produced with the same genes as the patient, stem cells from the embryo are not rejected by the patients body so they may be used for medic,a treatment.
What conditions are stem cell research helping?
- spinal cord injuries
- diabetes
- heart attack
- blindness
- damaged bones
