Cell division Flashcards
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Adult stem cell
def
A type of stem cell found in specific locations in adults. Adult stem cells can only differentiate into a limited number of related cell types
Benign tumour
def
A tumour that is not cancerous and cannot spread to other areas of the body
Bone marrow
def
Soft tissue found inside bones that produces new blood cells
Cancer
A disease caused by normal cells changing so that they grow and divide in an uncontrolled way. The uncontrolled growth causes a lump called a tumour to form
Cancer cells are undifferentiated – they do not carry out their normal function.
Carcinogen
def
A chemical or other agent which causes cancer
Cell cycle
def
The events that lead to cell division and DNA replication
Chromosome
def
The structure made of DNA that codes for all the characteristics of an organism.
Clone
def
An organism that is genetically identical to another organism
Daughter cells
def
Cells formed from the division of a cell
Diabetes
A serious disease in which the body is unable to regulate blood sugar
Differentiation
def
When an unspecialised cell becomes a more specialised cell type
DNA
def
Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being
Embryonic stem cell
def
A type of stem cell found in the embryo, capable of dividing into almost any cell type
Gene
def
The basic unit of genetic material inherited from our parents. A gene is a section of DNA which controls part of a cell’s chemistry - particularly protein production
Immune system
def
The body’s defence system against entry of any foreign body, including pathogens and agents such as pollen grains. The role of the immune system is to prevent disease
Ionising radiation
def
Radiation that is able to remove electrons from atoms or molecules to produce positively charged particles called ions
Malignant tumour
def
A fast-growing tumour that is cancerous and can invade and spread to other areas of the body
Meristem
def
A region in plant shoots and roots in which cells are dividing, and so are undergoing mitosis
Mitosis
Definition:
A type of cell division which produces daughter cells identical to the parent
In more detail:
Mitosis is a type of cell division in which a diploid body cell copies itself and finally divides into two identical diploid daughter cells. The daughter cells are clones of each other. Every base pair of their DNA is identical.
Multiple sclerosis
def
A disease which affects the brain and spinal cord and can make movement and communication difficult
Mutation
def
Arandom and spontaneous change in the structure of a gene, chromosome or number of chromosomes
Paralysis
def
The loss of muscle function in part of the body
Percentage growth chart
A chart used to compare the growth of a baby to the growth of other babies
Protein def and uses
Organic compound made up of amino acid molecules. One of the three main food groups, proteins are needed by the body for cell growth and repair
speciation
def
The formation of new and distinct species in the course of evolution
Stem cell
A cell found in foetuses, embryos and some adult tissues that can give rise to a wide range of other cells.
Stem cells are cells that have not undergone differentiation. A cell which has not yet become specialised is called undifferentiated.
Synthesise
def
Made or put together
Therapeutic cloning
Using cloning technology for medicinal purposes. One example is to use a person’s DNA to clone one of their organs for use in transplanting
Tumour
def
The lump of cells formed as a result of uncontrolled cell division
Ultraviolet
A high energy part of the electromagnetic spectrum associated with sunburn and skin cancer
Vacuole
def
A space within the cytoplasm of plant cells that contains cell sap
Zygote
def
A fertilised egg cell
Where does DNA exist?
For most of the time, DNA exists in the nucleus as thin strands.
How are chromosomes formed?
When the cells containing nuclei are ready to divide, the DNA copies itself then coils and condenses to form chromosomes.
What are chromosomes made of?
Each chromosome is made from a single molecule of DNA. Each section of this single molecule of DNA contains a code for the production of a particular protein called a gene.
How many chromosomes are in a (diploid) human cell contain?
Each human body cell contains 46 chromosomes. These can be arranged into 23 pairs. Each chromosome in a pair carries the same types of genes.
sex chromosomes
The 23rd pair is the sex chromosomes. In females, the two chromosomes are identical in shape. These are X chromosomes. Females are referred to as XX. In males, one of the chromosomes is different in shape. This is a Y chromosome. Males are referred to as XY.
Mitosis
when do cells divide?
Cells divide when:
- an organism grows
- an organism becomes damaged and needs to produce new cells for repair
- organisms like bacteria reproduce asexually
Cell cycle
The first stages of the cell cycle involve cell growth, then synthesis of DNA. The single strand of DNA that makes up each chromosome produces an exact copy of itself. After this a period of further growth occurs and the DNA is checked for errors. Mitosis occurs after this checking has been completed. Finally the cytoplasm of the cell separates and two cells are formed.
mitosis and the cell cycle
mitotsis is part of the cell cycle
The cell undergoes a type of cell division called mitosis. In mitosis, two cells called daughter cells are produced, each identical to the parent cell.
It is essential that any new cells produced contain genetic information that is identical to the parent cell.
When looking at cells with a microscope, the length of different stages of the cell cycle can be estimated using the formula for length of time in phase.
give formula.
length of time in phase = ((observed number of cells at that stage) ÷ (total number of cells observed)) x total length of time of cell cycle
How and why do cells divide? (human)
Cells grow then divide by mitosis only when we need new ones. This is when we’re growing or need to replace old or damaged cells.
Describe how cancer cells can invade surrounding tissue/describe the growth of malignant tumour in by mitosis.
(mean the same thing)
- malignant cells develop
- malignant cells divide and invade the surrounding tissues
Describe the spread of a tumour by metastasis/Tumour can cause the growth of second tumours. explain how.
(mean the same thing)
- the existing tumour secretes chemicals
- The chemicals stimulate the blood vessels to grow. They grow around the tumour
- Cancer cells detach from the tumour and are transported into the blood.
- A malignant cell squeezes through a blood capillary wall
- The cell divides; a secondary tumour starts to grow
How do carcinogens cause cancer?
Carcinogens cause cancer by damaging DNA. Carcinogens cause mutations to occur. A single mutation will not cause cancer. Several are required for this to occur. For this reason, we are more likely to develop cancer as we get older.
What is a risk factor?
Something that increases the likelihood of developing a disease is called a risk factor. There are several risk factors for various types of cancers including:
What lifestyle factors are risk factors for cancer?
- viruses linked with cancer, such as the human papilloma virus (HPV), being spread from person to person through sexual intercourse
- the chemical carcinogens in cigarette smoke increasing the risk of lung cancer
- alcohol intake is linked with certain cancers
- exposure to ultraviolet radiation, part of which is ionising, during sunbathing or outdoor activities, leading to the development of skin cancers
- diet, including fat and salt intake, increases the risk of cancer
Industrial and environmental factors at work that are risl factors for cancer.
- exposure to ionising radiation increases the risk factor
- exposure to chemical carcinogens
How are multicellular organisms (Animals and plants produced by sexual reproduction) produced?
Animals and plants produced by sexual reproduction begin life as a single cell, a fertilised egg or zygote. These cells must divide by mitosis to produce a multicellular organism.
mitosis in plants and animals
Mitosis happens throughout the bodies of animals but only occurs in specific regions of plants. These are called meristems and are found in the tips of roots and shoots. Here new cells are formed.
What id cell elongation and what does it occur/not occur in?
Plant cells are able to become longer as they grow. This process is called cell elongation and occurs throughout the plant, not just in the meristems. Cell elongation does not occur in animals.
differentiation of cells in multicelluar organisms.
Why?
What does it happen in?
what are cells that have become differentiated called?
The cells of multicellular animals and plants must differentiate, so that its cells develop features that enable them to fulfil specific roles. Cells that have differentiated have become specialised. Without this specialisation, complex multicellular animals and plants would not exist.
Examples of specialised cells in animals. cells of the:
- Circulatory system
- Excretory system
- Muscular system
- Nervous system
- Respiratory system
- Reproductive system
- Skeletal system
specialisation of animals cells.
what are the cells of the Circulatory system specialised to do?
- Transport substances.
- Defend the body.
- Regulate temperature.
specialisation of animals cells.
what are the cells of the Excretory system specialised to do?
- Remove waste products and unwanted substances.
- Regulate the water content of the body.
specialisation of animals cells.
what are the cells of the Muscular system specialised to do?
Bring about movement.
specialisation of animals cells.
what are the cells of the Nervous specialised to do?
- Respond to internal and external stimuli and conditions.
- Carry messages for the body to work as a coordinated whole.
specialisation of animals cells.
what are the cells of the Respiratory system specialised to do?
Deliver oxygen for respiration and remove waste.
specialisation of animals cells.
what are the cells of the Reproductive system specialised to do?
Bring about fertilisation to produce new offspring.
specialisation of animals cells.
what are the cells of the Skeletal system specialised to do?
- To bring about movement.
- Support and protect internal structures.
- Produce blood cells.
- Store and release calcium.
Examples of specialised cells in plants.
In the leaf:
- Palisade mesophyll
- Spongy mesophyll
- Guard cells
Specialisation of plant cells.
What are the cells of the Palisade mesophyll tissue specialised to do?
(palisade cells that make up the mesophyll)
Carry out photosynthesis.
Specialisation of plant cells.
What are spongy mesophyll cells specialised to do?
- Allow gases to circulate for the exchange of gases between the leaf and the environment.
- Carry out photosynthesis.
Specialisation of plant cells.
What are Guard cells specialised to do?
Open and close to control the exchange of gases – carbon dioxide, water vapour and oxygen.
Examples of specialised cells in plants.
In the phloem:
- Sieve tubes
- Companion cells
Specialisation of plants cells.
What are sieve tubes specialised to do?
Transport products of photosynthesis, including sugars and amino acids, from the leaf to where they are needed.
Specialisation of plant cells.
What are companion cells Specialised to do?
Provide the energy required for transporting substances in sieve tubes.
Give and example of a specialised cell in the xylem and what it is specialised to do.
Xylem vessels.
Specialised to transport water and dissolved minerals from the roots, up the plant.
Give and example of a specialised cell in growing plants and what it is specialised to do.
Meristem.
Specialised to produce new cells as they divide.
Monitoring growth.
in which ways can the growth of babies be measured?
how can the growth of babies in all of these measurements me monitored?
The growth of babies is measured in the following ways:
- Mass (kg)
- Length (cm)
- Head circumference (cm)
The growth of babies in all three of these measurements can be monitored using percentile growth charts.
What are the stages of mitosis?
1) Interphase
2) Prophase
3) Metaphase
4) Anaphase
5) Tekphase
6) Cytokinesis
What happens during the first stage of mitosis (Interphase)?
The cell spends most of its life in this phase. The DNA in chromosomes copies itself ready for mitosis.
What happens during the second stage of mitosis (Prophase)?
The DNA in chromosomes and their copies condenses to become more visible. The membrane around the nucleus disappears.
What happens during the third stage of mitosis (metaphase)?
Chromosomes and their copies line up in the middle of the cell.
What happens during the fourth stage of mitosis (anaphase)?
Chromosomes and their copies are pulled to different ends of the cell.
What happens during the fifth stage of mitosis (telophase)?
New membranes form around the chromosomes at each end of the cell.
What happens during the sixth stage of mitosis (cytokinesis)?
The cell membrane pinches in and eventually divides into two daughter cells.
Some adult stem cells remain in the bodies of adults. These are found in limited numbers at certain locations in the body. Adult stem cells can be found in:
- nose
- brain
- eyes
- blood
- heart
- liver
- bone marrow
- skin
- muscle
Differentiation of adult stem cells.
Adult stem cells can differentiate into related cell types only. So bone marrow cells can differentiate into blood cells and cells of the immune system, but not other cell types.
Stem cells in plants
Meristem
Cell division in plants occurs in regions called meristems. Cells of the meristem can differentiate to produce all types of plant cells at any time during the life of the plant. The main meristems are close to the tip of the shoot, and the tip of the root.
What happens to cells produced in plants from the division of a meristem cell?
- One cell remains meristematic
- The other contributes to growth.
How are vacuoles formed?
link to stem cells in plants
In a growing shoot, new cells are being produced continuously near the tip. As the cells become older, further away from the tip, they become differentiated. They enlarge and develop a vacuole.
Use of stem cells in medicine.
Why we use stem cells.
Examples of what they are used to treat.
Stem cells can divide to produce new cells, which can then divide into different cell types. They therefore have the potential to be transplanted into patients to treat medical conditions and disease. They could be used to replace cells that have been damaged or destroyed, eg:
- in type 1 diabetes
- in cases of multiple sclerosis, which can lead to paralysis
- in cases of spinal cord or brain injury, that have led to paralysis
What is the best source of embryonic stem cells?
The best source is a five-day-old embryo, although there are clinical, ethical and social issues with their use.
common example of use of adult stem cells and in what circumstances they are needed.
Bone marrow transplants are an example of adult stem cell transplant. Bone marrow cells will differentiate into different types of blood cell. Bone marrow transplants are carried out:
- in cases of blood cell cancer such as leukaemia and lymphoma
- when blood cells have been destroyed by cancer treatment
Potential uses of stem cells.
- treating patients with currently untreatable conditions
- growing organs for transplants
- medical research
clinical issues with the use of stem cells.
whether Embryonic, adult or therapeutically cloned
- There is no guarantee of how successful these therapies will be, for example in the use of stem cells in healing damage caused by Parkinson’s disease.
- The 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 to behave like cancer cells.
- Cultured stem cells could be contaminated with viruses which would be transferred to a patient.
ethical issues with the use of stem cells.
whether Embryonic, adult or therapeutically cloned
- A source of embryonic stem cell 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 could develop into a person.
- At what stage of its development should an embryo be regarded as, and treated as, a person?
social issues with the use of stem cells.
whether Embryonic, adult or therapeutically cloned
- Educating the public about what stem cells can, and can’t do, is important.
- Whether the benefits of stem cell research 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 developmental stages.
What is the first step in the cell cycle?
Cell growth
