B2 - Cell Division Flashcards
Which stem cells are found in animals?
Adult stem cells
Embyonic stem cells
What are stem cells?
Cells divided by mitosis that are able to differentiate into specialised cells
What can embryonic cells differentiate into?
Any type of specialised cell
What happens to your stem cells when you stop producing embryonic stem cells?
They can no longer differentiate into absolutely anything
What can adult stem cells do?
They can divide by mitosis but can only differentiate into different types of blood cells
How many chromosomes does the human body have in each nucleus?
46 chromosomes (23 pairs of 2)
What is differentiation?
The process by which a cell changes to become specialised
What forms when a sperm cells fertilises an egg cell?
A single cell called a zygote
How is an embryo made?
A zygote divides continously by mitosis and in a few days, there is enough cells to form an embryo
What are one of the group of cells in an embryo called?
Embryonic stem cells
What can adult stem cells only differentiate into?
Different types of blood cells
Where are adult stem cells found?
In the bone marrow
Since adult stem cells cant form any new tissues like embryonic stem cells, what is their purpose?
They can replace damaged cells to keep us alive
Where are plant stem cells found?
Plant tissues called ‘meristems’
Where are meristems found?
Areas of the plant that are continuously growing
E.g. tip of roots and tip of (shoots) leaves
What are some examples plant stem cells can differentiate into?
Palisade cells
Phloem cells
Xylem cells
What is Binary fission?
The process by which prokaryotic organisms, like bacteria, divide and reproduce
Is BINARY FISSION the same as MITOSIS?
No
Why is Binary fission and mitosis NOT the same?
Mitosis is the process that happen in EURKARYOTIC cells
Binary fission is the process that happens in PROKARYOTIC cells
Why is Binary Fission a type of reproduction?
The worn organism has to split into two organisms
What type of reproduction is Binary Fission referred to?
Asexual Reproduction
What does a bacterial cell need to do in order to divide?
GROW to be big enough to divide into two new cells
REPLICATE ITS GENETIC MATERIAL so there is enough for each new cell
How does bacteria divide after it grows and replicates its genetic material?
The two circular chromosomes (original and clone) move away from each other, getting ready to create new cell walls and pull apart
If a bacterial cell has a mean dividion time of 30 minutes. How many cells would it produce in 3 hours?
180 mins in 3 hours
6 rounds of division in 3 hours
1x2x2x2x2x2x2 = 64
64 cells
What conditions do bacteria like for optimal growth?
Somewhere that is:
Warm
Moist
Has plenty of nutrients
If bacteria are in bad conditions for optimal growth what will happen to their division rate?
They will divide more slowly or not at all
What is the first stage of the cell cycle?
The DNA replicates to form two copies of each chromosome
The cell then grows and copies its internal structures (mitochondria, ribosomes etc.)
What is the second stage of the cell cycle?
Mitosis takes place
The two sets of chromosomes is pulled to each end of the cell
What happens in the third and final stage of the cell cycle?
The cytoplasm and cell membrane divide to form two identical cells
Why is mitosis essential to animals and plants?
Essential for growth and development of multicellular organisms
What type of reproduction method does mitosis occur in?
Asexual reproduction
How are adult stem cells used in medicine?
Used to cure disease
What is an example of adult stem cells being used in medicine?
Transferring stem cells from bone marrow from a healthy person to replace faulty blood cells in a patient who needs them
What are the advantages of therapeutic cloning?
An embryo is made to have the same genetic material as the patient
Wouldnt be rejected by the patients body
What age are adult stem cells found in?
People of all ages
What is the idea of using stem cells in medicine
To replace faulty cells
What are the disadvantages of using embryonic stem cells in medicine?
Ethical issues
Patients immune system might reject them
What is a disadvantage of using adult stem cells in medicine?
Can only treat blood diseases
What is an advantage of using adult stem cells in medicine?
Taken from the patient so it wont be rejected by their immune system
What are the risks involved when using stem cells in medicine?
Virus transmission
Tumor development - chance they could divide uncontrolably
Why do people reject the use of embryonic stem cells in research?
Embryos have fge potential for human life
Why do body cells normally have two copies of each chromosome?
One from the mother and one from the father
What are the daughter cells in mitosis?
The two identical cells made from the original one
What is the name of the cell division prokaryotic cells use to reproduce?
Binary fission
Explain the process of Binary fission
The circular DNA and plasmids replicate
The cells grows and the circular DNA stands move to opposite ends
Cytoplasm begins to divide and new cell memranes form
Two daughter cells are produced with random copies of plasmids
What happens in a culture medium?
Area of nutrients so bacteria culture (grow)
What culture medium do you use in the culturing microorganisms practical?
Agar jelly
Why are culture mediums not kept above 25°C?
Possibility of harmful pathogens growing
How do you culture microorganisms (grow bacteria)?
Put a culture medium like hot agar jelly in a petri dish
When the agar jelly cools use inoculating loops to transfer microorganism to the culture medium
Use a dropping pipette and spreader to get an even covering of bacteria
The microorganisms then multiply
What are some antiseptic technique?
Sterillizing equipment - dip in ethanol and then use bunsen burner to burn off bacteria
Opening petri dish slightly
Clean surfaces
A gene is a length of DNA. What type of subdtance does a gene code for?
Protien
Most human body cells contain 6 × 10* –12 grams of DNA.
What mass of DNA will a human sperm cell contain?
3 x 10* -12
What is the name of the type of cell division that produces sperm cells?
Meiosis
What are the advantages of embryonic stem cells in medicine?
Can treat a wide variety of diseases
Can differentiate into any cell
What is Therapeutic cloning?
A process of creating stem cells with the same genes as thr patient to prevent rejection
What is the process of Therapeutic Cloning?
Use a human skin cell as an example.
Nucleus is taken out the skin cell and put in an egg cell
The egg develops into an embryo
Stem cell can now differentiate into any cell
There are two types of cell division: mitosis and meiosis.
(a) Describe three differences between the processes of mitosis and meiosis.
Mitosis produces two daughter cells whereas meiosis produces 4
Mitosis produces cells with 23 pairs (46) chromosomes whereas meiosis produced cells with 23
Mitosis produces genetically indentical cells whereas meiosis produces genetically different cells
