Cell Division Flashcards
What do chromosomes do?
They carry genetic information in a molecule called DNA
When a cell divides, what does mitosis ensure about the cell genetic information?
That the genetic information is the same
Where is DNA?
In cells nucleus within chromosomes
What is a gene?
The code for the production of a protein within each section of a chromosome
How many chromosomes are in the human body and how are they arranged?
There are 46 chromosomes arranged into 23 pairs
What are the genes like in each of the 23 pairs of the human body cell?
They have the same types of genes
The 23rd pair of chromosomes in the human body cell are what chromosomes
Sex chromosomes
What are the chromosomes like within females?
They are identical in shape
What are female chromosomes often referred to as?
XX
What are the chromosomes like in a man?
They are different in shape there is an X and Y chromosome
What are the chromosomes referred to in a man?
XY
Describe the structure of a DNA
It is a polymer made up of molymers called ACGT
What does ACGT stand for
Adenine, cytosine. Guanine and thymine
What are the stages of the cell cycle?
Cell growth DNA synthesis further growth mitosis the cytoplasm separates and a temporary cell resting period
When do cells divide?
When an organism grows or an organism is damaged and needs to produce new cells
What happens in DNA synthesis?
The single strand of DNA that makes up chromosome produces an exact copy of itself
What happens to the nuclear membrane during mitosis?
It breaks down
What happens to the chromosomes at the end of mitosis?
They are pulled to each end of the cell
What cell structures divide in mitosis?
Nucleus, cytoplasm and cell membrane
What is formed at the end of mitosis?
Two identical daughter cells
How do you calculate the length of time in phase?
Observed numbers of cells of that stage over total number of cells observed times by total length of time of cell cycle
What are the six stages of the cell cycle?
Interphase prophase metaphase anaphase telophase cytokinesis
What happens during interphase?
The DNA copies itself and the cell enlarges and is checked for errors
What happens in prophase?
The cell prepares itself by condensing DNA into chromosomes and it breaks down the nucleus
What is metaphase?
Chromosomes line up across the middle of the cell
What is anaphase?
The chromosome are pulled to opposite ends of the cell
What is Telophase?
Nuclear membranes form around the chromosomes at each end of the cell
What is cytokinesis?
The cell divides down the middle to become two new cells
Gamete cells contain half the genetic material so what type of cells are they?
Haploid
What are gamete cells used for?
Sperm cells in males and egg cells in females
How many divisions happen in meiosis
2
How many gamete cells are made in meiosis?
4 genetically unique cells
Mother chromosomes are referred to as what
Maternal chromosomes
What are father chromosomes referred to as?
Paternal chromosomes
What is a stem cell?
Cells that haven’t undergone differentiation so aren’t specialised but undifferentiated
Cells that are removed from the embryo are called… and what can they do
Embryonic cells and can differentiate into any cell type
Where are adults stem cells found?
In brain eyes, blood heart, liver bone marrow skin and muscle
Adult stem cells can differentiate into what cell types
Related cell types
Where does cell division in plants occur?
In the Meristems
What can cells of the meristem differentiate into?
All types of plant cells
Where are the main Meristems close to?
The tip of the shoot and root
What are cells of the circulatory system differentiated for?
The transport substances defend the body and regulate temperature
What are cells of the excretory system differentiated for?
To remove waste products and unwanted substances regulate water content of body
All the cells of the muscular system differentiated for?
Bring about movement
What are cells of the nervous system differentiated for ?
To respond to internal and external stimuli and conditions to carry messages for the body to work
What are cells of the respiratory systems differentiated for ?
Deliver oxygen for respiration and remove waste
What are cells in the reproductive system differentiated for ?
To bring about fertilisation to produce new offspring
What are cells in the skeletal systems differentiated for?
To bring about movement support and protecting internal structures to produce blood cells and store and release calcium
What are cells in the Palisades mesophyll differentiated for?
To carry out photosynthesis
What are cells of the spongy Mesophyll differentiated for?
Allow gases to circulate for the exchange of gases between the leaf and the environment carry out some photosynthesis
What are cells of the guard differentiated for ?
Open and close to control gas exchange
What are cells of the sieve tubes differentiated for ?
The transport products of photosynthesis like sugars and amino acids
What are cells of companion cells differentiated for ?
Provide energy for transporting substances in sieve tubes
What are cells in Xylem vessels differentiated for
For transporting water and dissolved minerals
What are cells in the meristem differentiated for ?
Produce new cells as they divide
Why are plants cloned ?
To produce identical plants quickly and economically
What are some examples of medical conditions and diseases that stem cells can be transplanted to help prevent?
Type one diabetes cases of multiple sclerosis that paralysis of spinal cord or brain injury
Give properties of embryonic stem cells in terms of transplants
Difficult to obtain but differentiate into a wide range of cell types
What bone marrow transplants have been carried out
Cases of blood cell cancer and when blood cells are destroyed by cancer treatment
Therapeutic cloning and what does it involve?
Therapeutic cloning can produce stem cells with the same genetic make up as a patient. It involves a transfer of a nucleus from a cell of the patient to an egg cell whose nucleus has been removed.
What are some clinical issues of therapeutic cloning?
There is no guarantee how successful these therapies will be the current difficulty in finding suitable stem cell donors the difficulty in obtaining and storing a patient’s embryonic stem cells. Mutations have been observed in stem cells cultured for a number of generations and some mutated stem cells have been observed behave, like cancer cells and cultured stem cells could be contaminated with viruses which could be transferred to a patient
What are some ethical issues of therapeutic cloning
A source of embryonic stem cells is unused embryos produced by in vitro fertilisation for therapeutic cloning. Is it right to create embryos for therapy and destroy them in the process? Embryos could come to be viewed as a commodity and not as an embryo that developed into a person what stage of its development should an embryo be regarded as and treated as a person?
Social issues of therapeutic cloning
Educating the public about what stem cells can and can’t do is important whether the benefits of stem cell use outweigh the objections much of the research is being carried out by commercial clinics so reported successes are not subject to peer review patients could be exploited by paying for expensive treatments and being given false hope of a cure as stem cell therapies are only in their development stages
