Cells And Control Flashcards
Most of the time where does DNA exist!?
In the nucleus as thin strands
When the cells containing nuclei are ready to divide what happens to the DNA!?
It copies itself then could and condenses to form chromosomes
What is DNA!?
Deoxyribonucleic acid. The material inside the nucleus of cells, carrying the genetic information of a living being.
What are chromosomes!?
The structure made of DNA that codes for all the characteristics of an organism.
How many chromosomes does each human body cell contain!?
46 chromosomes
How many chromosomes are in a pair!?
23
Each chromosome in a pair carries the same types of what!?
Genes
What is the 23rd pair!?
The sex chromosomes
Describe the pair of chromosomes in females….
the two chromosomes are identical in shape. These are X chromosomes. Females are referred to as XX
Describe the pair of chromosomes in a male…..
In males, one of the chromosomes is different in shape. This is a Y chromosome. Males are referred to as XY.
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
What is essential that new cells contain!?
It is essential that any new cells produced contain genetic information that is identical to the parent cell.
What is the cell cycle!?
The events that lead to cell division and DNA replication.
What is the equation for length of time in a phase!?
Observed number of cells at that stage/total number of cells observed x total length of time of cell cycle
What is the definition of mitosis!?
A type of cell division which produces daughter cells identical to the parent.
Describe the process of mitosis!?
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.
What happens in the first phase of the cell cycle and what is it called!?
Interphase
The cell spends most of its life in this phase. The DNA in chromosomes copies itself ready for mitosis.
What happens in the second stage of the cell cycle !? And what is it called!?
Prophase
The DNA in chromosomes and their copies condenses to become more visible. The membrane around the nucleus disappears.
What happened in the third stage of the cell cycle !? And what is it called!?
MetaphaseChromosomes and their copies line up in the middle of the cell.
What happens in the fourth stage of the cell cycle and what is it called!?
Anaphase
Chromosomes and their copies are pulled to different ends of the cell
What is the fifth stage of the cell cycle!?
Telophase
New membranes form around the chromosomes at each end of the cell.
What happens it final stage of the cell cycle!?
CytokinesisThe cell membrane pinches in and eventually divides into two daughter cells.
What 4 stages of the cell cycle are part of mitosis!?
prophase, metaphase, anaphase and telophase.
When do cells use mitosis!?
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.
What happens when a cell becomes cancerous!?
When a cell becomes cancerous, it begins to grow and divide uncontrollably. New cells are produced even if the body does not need them. A group of cancerous cells produces a growth called a tumour.
What are the 2 types of tumour!?
Benign and malignant
What is the definition of benign!?
A tumour that is not cancerous and cannot spread to other areas of the body.
What are the characteristics of a benign tumour!?
Grow slowly.
Usually grow within a membrane, so can easily be removed.
Do not invade other parts of the body.
What is the definition of a malignant tumour!?
A fast-growing tumour that is cancerous and can invade and spread to other areas of the body.
What are the characteristics of a malignant tumour!?
Grow quickly.
Invade neighbouring tissues and can spread to other parts of the body in the bloodstream.
As the tumour grows, cancer cells detach and can form secondary tumours in other parts of the body.
This process is called metastasis.
Are cancer cells specialised or undifferentiated!?
Cancer cells are undifferentiated – they do not carry out their normal function.
At some point what may occur due to cancer!?
At some point, secondary tumours may develop
What causes cancer!?
Genetic factors
Chemicals and other agents called carcinogens
What is a carcinogen!?
chemical or other agent that causes cancer.
What do carcinogens cause!?
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.
List the lifestyle factors that are likely to cause cancer…..
viruses
the chemical carcinogens
alcohol intake
exposure to ultraviolet radiation
diet
Give an example of viruses that can unfortunately lead to cancer….
viruses linked with cancer, such as the human papilloma virus (HPV), being spread from person to person through sexual intercourse
Give an example of a chemical carcinogen that can unfortunately lead to cancer!?
the chemical carcinogens in cigarette smoke increasing the risk of lung cancer
Give an example of how alcohol can unfortunately lead to cancer!?
alcohol intake is linked with certain cancers
Give an example of how exposure to ultraviolet light can unfortunately cause cancer!?
exposure to ultraviolet radiation, part of which is ionising, during sunbathing or outdoor activities, leading to the development of skin cancers
Give an example of how diet can unfortunately lead to cancer……
diet, including fat and salt intake, increases the risk of cancer
List the industrial and environmental factors at work that can unfortunately lead to cancer…..
exposure to ionising radiation increases the risk factor
exposure to chemical carcinogens
What is another type of risk that can unfortunately potentially lead to cancer!?
There are also genetic risk factors for some cancers.
How are plants and animals produced!?
Animals and plants produced by sexual reproduction begin life as a single cell, a fertilised egg or zygote.
How must plants and animals use mitosis!?
These cells must divide by mitosis to produce a multicellular organism.
What is a zygote!?
A fertilised egg cell.
Where does mitosis occur in animal cells!?
Mitosis happens throughout the bodies of animals
Where does mitosis occur in plants!?
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 is a meristem!?
A region in plant shoots and roots in which cells are dividing, and so are undergoing mitosis.
What is cell elongation!?
Plant cells are also able to become longer as they grow. This process is called cell elongation
Where does cell elongation occur in a plant!?
occurs throughout the plant, not just in the meristems.
Does cell elongation occur in animals!?
No
What must multicellular animals and plants also do!?
Differentiate
Why must multicellular plant and animal cells differentiate!?
so that its cells develop features that enable them to fulfil specific roles. Cells that have differentiated have become specialised
What does differentiate mean!?
When an unspecialised cell becomes a more specialised cell type.
What would happen if plant and animal cells didn’t become specialised!?
Without this specialisation, complex multicellular animals and plants would not exist.
What are cells in the circulatory system specialised to do!?
Transport substances. Defend the body. Regulate temperature.
What are cells in the excretory system specialised to do!?
Remove waste products and unwanted substances. Regulate the water content of the body.
What are cells of the muscular system specialised to do!?
Bring about movement
What are cells of the nervous system specialised to do!?
Respond to internal and external stimuli and conditions. Carry messages for the body to work as a coordinated whole.
What are the cells of the respiratory system specialised to do!?
Deliver oxygen for respiration and remove waste.
What are the cells of the reproductive system specialised to do!?
Bring about fertilisation to produce new offspring.