Unit 2 Cells Specialisation and Divisions Flashcards
What is special about the first group of cells within an embryo?
They are all identical
After the embryo matures what happens to the initial identical cells?
The cells become specialised to a specific role or function
How are all the cells in the human body produced from a fertilised egg?
The cells divided by mitosis
What does specialisation of the cell do?
Specialisation of the cell allows the cell to become more suited for its role
If all the cells divided through mitosis what does the mean each cell contains?
Each cell contains the same genes
What allows each cell to become specialised?
Each cell has the same genes however if the genes are expressed or not can allow the cell to become suited for its function
What is different about the specialised cells for each particular role that it carries out?
The shape of the cell is different and the number of organelles are all different
Why does a sperm cell have more mitochondria than an epithelial cell?
Sperm cell has more mitochondria because it needs to release more energy for cellular respiration in order for it move due to the flagellum
What is a type of tissue found in the animal cell?
Epithelial tissue
What do epithelial tissues do?
Epithelial tissues line the surface of organs and have a protective or secretory function
What is the relation between the function of cilia and the epithelial tissue?
The cilia are used to move mucus along the epithelial surfaces
What is the similar epithelial tissue in plants?
The xylem
What is the function of the xylem in plants?
The xylem is used to transport water and mineral ions around the plant as well as give structural support
What are the 3 things that an organ is made up of in an animal cell?
Muscles
Epithelial tissue
Connective tissue - Hold other tissues together in place
What are the 5 things that an organ is made up of in a plant cell?
Palisade mesophyll - palisade cells that carry out photosynthesis
Spongy mesophyll - Gaseous diffusion
Epidermis - Protect the leaf and allow gaseous diffusion
Phloem - To transport organic material around the cells
Xylem - To transport water and mineral ions to the cell
What are 2 transport tubes that are classified as organs?
The arteries and veins
Are Blood Capillaries also classified as organs?
No because blood capillaries have a smaller size difference and therefore have a lower capacity
What does the digestive system do and consist of?
The digestive system digests and processes foods and it includes the salivary glands, oesophagus, stomach, duodenum, ileum, pancreas and liver
What does the respiratory system do and consist of?
The respiratory system is used for breathing and gas exchange and it consists of the trachea, bronchi, bronchioles, alveoli and the lungs
What does the circulatory system do and consist of?
The circulatory system is used for pumping and circulating blood and it consists of the heart, arteries and veins
What are the 2 ways that a cell can be divided?
Mitosis or meiosis
What does Mitosis produce?
Mitosis produces two daughter cells that have the same number of chromosomes as each other and the parent cell
What does Meiosis produce?
Meiosis produces four daughter cells that have half the number of chromosomes as the parent cell
What is the exception that mitosis does not produce identical daughter cells?
Mitosis will produce 2 daughter cells that are not identical due to a mutation which could lead to a difference in DNA between the identical cells
What is the stage in which a cell grows its organelles and does not divide?
Interphase
What is the place where two copies of DNA join together?
The centromere of a chromosome
What are the 4 phases after the interphase called?
The prophase, metaphase, anaphase and telophase
What are visible in the prophase?
The chromosomes start to become visible
What happens in the prophase? (1)
The chromosomes are visible as thin threads which start to shorten and thicken
What happens in the prophase? (2)
Animal cells contain 2 cylindrical organelles called centrioles which move to opposite ends of the cells
What happens in the prophase? (3)
Spindle fibres are made at each end of the centrioles at the opposite ends, collectively the spindle fibres together create a structure celled the spindle apparatus
What happens in the prophase? (4)
The nucleolus disappears and the nuclear membrane breaks down to allow the chromosomes to be free in the cytoplasm.
What happens in the prophase? (5)
These chromosomes are drawn towards the equator of the cell by the spindle fibres attached to the centromere
Which phase is after the prophase?
The metaphase
How are the chromosomes seen to be in the metaphase?
The chromosomes are seen to be made up of 2 chromatids
What is each chromatid an identical copy of?
Each chromatid is the identical copy of DNA from the parent cell
What are the chromatids joined by?
The centromere
What happens in the metaphase? (1)
The centromere has some microtubules from the poles attached to it which allows the chromosomes to be pulled along the spindle apparatus to arrange themselves along the equator of the cell
What phase is after the metaphase?
Anaphase
What happens in the anaphase? (1)
The centromere divides into two and the spindle fibres pulls the individual chromatids making a single whole chromosome
Where is the energy for the process of pulling the chromatids apart come from?
Cellular respiration from the release of energy from glucose that comes from mitochondria
Where are the mitochondria gathered around when the anaphase process occurs?
The mitochondria are gathered around the spindle fibres
What happens if a chemical destroys the spindle within a cell?
The chromosomes are unable to reach the opposite poles of the cells and therefore remain at the equator of the cell
What is the phase after the anaphase?
The telophase
What happens in the telophase? (1)
The chromosomes reach their respective poles and become longer and thinner finally disappearing altogether leaving the chromatin widely spread
What happens in the telophase? (2)
Next, the spindle fibres disintegrate and the nuclear envelope and nucleolus re-form.
What is the process after telophase called and what happens in it?
Cytokinesis is the process of the cytoplasm dividing
Describe how prokaryotic cells divide through binary fission? (1)
The circular DNA molecule replicates and both attaches to the cell membrane
Describe how prokaryotic cells divide through binary fission? (2)
The plasmids replicate
Describe how prokaryotic cells divide through binary fission? (3)
The cell membrane begins to grow between the 2 DNA molecules and pitches inwards, dividing the cytoplasm in two
Describe how prokaryotic cells divide through binary fission? (4)
A new cell wall then forms in between the 2 DNA molecules dividing the the original cell into two daughter cells, each with a single copy of DNA and variable number of plasmids
What is cancer?
Cancer is a group of diseases caused by a growth disorder in cells
What leads to the uncontrolled growth and division of cells?
The damage of genes that help in the process of mitosis and the cell cycle
What forms as a result of uncontrolled growth?
Tumours - a group of abnormal cell that constantly expands in size
What stage is cancer considered cancerous?
From benign to malignant
Why does the size of a tissue need to be bigger?
So that the cells can divide by mitosis for the use in repairing dead or worn out cells and for growth during the development of the organism
How is the rate of mitosis affected?
By external growth factors such as the environment and the growth of the cell and the two type of genes that control this
Describe how malignant tumours can become life-threatening?
Malignant tumours grow rapidly producing clone of themselves so they spread to other parts of the body faster
What does the treatment of cancer involve?
Cancer Treatment involves the blocking of the cell cycle by killing cells in the dividing process which can disrupt the cancer growth
What are the 2 ways in which the cell cycle can be disrupted?
1) Preventing the DNA from being replicated
2) Inhibiting the metaphase stage by interfering with the spindle formation
What is the disadvantage of cancer treatment such as chemotherapy?
Chemotherapy targets cancerous cells that have high division time during mitosis but can however also affect the the cells with high division times such as normal hair cells
