Cell Division Flashcards
When do cells divide?
An organism grows
An organism becomes damaged and needs to product more cells for repair
Organisms like bacteria reproduce asexually
What’s a cell cycle?
When a growing and dividing cell goes through a series of stages
Give the stages of the cell cycle
Cell growth, DNA synthesis, further growth occurs, mitosis, cytoplasm separates, temporary cell resting period of the cell stops dividing
What happens in DNA synthesis?
The chromosomes are now double stranded
What happens in the further growth?
DNA is checked for errors
Give the formula for length of time in phase
Observed number of cells / total number of cells observed X total length of time of cell cycle
What is mitosis?
A type of cell division in which a diploid body cell copies itself and finally divides into 2 daughter cells
Give the stages of mitosis
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
What happens in interphase?
DNA is copied
What happens in prophase?
DNA becomes more visible. Membrane around the nucleus disappears
What happens in metaphase?
Chromosomes and their copies line up in the middle of the cell
What happens in anaphase?
Chromosomes and their copies are pulled to different ends of the cell
What happens in telophase?
New membranes form around the chromosomes at each end of the cell
What happens at cytokinesis?
The cell membrane pinched in, separating the two daughter cells
When do we need mitosis?
When we’re growing or need to replace old damaged cells
What happens when a cell becomes cancerous?
The cell begins to grow and divide uncontrollably
What’s a tumour?
A growth caused by cancerous cells
Give the types of tumour
Benign and malignant
Give the characteristics of a benign tumour
Grows slowly. Usually easily removed as it grows within a membrane
Doesn’t invade other parts of the body
Give the characteristics of a malignant tumour
Grows quickly
Invades neighbouring tissues and can spread to other parts of the body through the bloodstream
As it grows, cancer cells detach and can form secondary tumours in other parts of the body (metastasis)
What’s a carcinogen?
A chemical or other agent that causes cancer
How do carcinogens cause cancer?
By damaging DNA and causing mutations to occur
Give the lifestyle factors for the risk factors of various cancers
-through sex
-smoking
-alcohol
-exposure to ultraviolet-ionising-during sunbathing
-diet(fat)
Give the industrial and environmental factors of the risk factors that cause cancer
-exposure to ionising radiation increases the risk factor
-exposure to chemical carcinogens
Give an example of when mitosis happens in plants
In meristem cells- a region in plant shoots and roots in which cells are dividing, so undergoing mitosis
What’s cell elongation?
When plant cells are able to become longer as they grow-occurs throughout the plant
Give examples of animal cells that differentiate?
Circulatory system
Excretory system
Muscular system
Nervous system
Respiratory system
Reproductive system
Skeletal system
How are circulatory system cells specialised?
Transport substances. Defend the body. Regulate temperature
How’s the excretory system cells specialised?
They remove waste. Regulate the water content of the body
How are muscular system cells specialised?
They bring about movement
How are the nervous system cells specialised?
Respond to stimuli or conditions
Carry messages for the body to work as a coordinated whole
How are respiratory system cells specialised?
Deliver oxygen for respiration and remove waste
How are reproductive system cells specialised?
Bring about fertilisation to produce new offspring
How are skeletal system cells specialised?
Bring about movement. Support + protect internal structures. Produce blood cells. Store and release calcium
Give examples of specialised cells in plants
In leaf -palisade mesophyll, spongy mesophyll, guard cells
In phloem- sieve tubes, companion cells
In xylem- xylem vessels
In growing points- meristem cells
How’s palisade mesophyll cells specialised ( in leaf)?
Carries out photosynthesis
How’s spongy mesophyll cells specialised( in leaf)?
Allows gases to circulate for exchange of gases between the leaf and environment.
Carries out photosynthesis
How are guard cells specialised (in leaf)?
Open and close to control the exchange of gases- carbon dioxide, water vapour and oxygen
How are sieve tubes cells specialised(phloem)?
Transports products of photosynthesis (sugars and amino acids) from leaf to where they’re needed
How’re companion cells specialised(in phloem)?
Provides energy needed for transporting substances in sieve tubes
How are xylem vessels specialised( in xylem)?
Transports water and dissolved minerals from the roots up to the plant
How are meristem cells specialised(in growing points)?
Produce new cells as they divide
How is the growth of babies measured?
1) mass(kg)
2) length(cm)
3) head circumference(cm)
What’re stem cells?
Cells that haven’t undergone differentiation
What’s an embryonic stem cell?
A type of stem cell ground in the embryo, capable of dividing into almost any cell type
What’re adult stem cells?
A type of stem cell found in specific locations in adults- only differentiate into a limited number of related cell types
Give a few examples of where adult stem cells can be found
-nose
-brain
-eyes
-blood
-heart
-liver
-bone marrow
-skin
-muscle
Give an example of what adult stem cells can differentiate into in bone marrow
Blood cells and cells of the immune system
Give benefits associated with the use of stem cells in medicine
-treating patients sit currently untreatable conditions
-growing organs for transplants
-medical research
Give some clinical issues of using stem cells in medicine
-no guarantee of how successful these therapies will be (eg. Use of stem cells healing damage caused Parkinson’s)
-difficulty finding donors
-difficulty of storing patients embryonic stem cells
-mutations could happen
-cultured stem cells could be contaminated with viruses which could be transferred to a patient
Give some ethical issues with using stem cells in medicine
-Source of embryonic stem cell is unused embryos produced by vitro fertilisation
-for therapeutic cloning, is it right to create embryos and destroy them in the process
-embryos could come to be viewed as a commodity- not as an embryo that could develop to a person
-what stage of its development should an embryo be regarded as,and treated as, a person?
Give some social issues of using stem cells in medicine
-educating the public about what stem cells can and can’t do is important
-whether the benefits outweigh the objections
-much of the research is being carried out by commercial clinics- reported successes aren’t subject or 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 developmental stages
What’s a body cell?
All our cells other than gametes
What are gametes
Sperm in males and eggs in females
