Biology : Cells and Control Flashcards
What do chromosomes contain?
Genetic Information
What are chromosomes?
Coiled up lengths of DNA molecules
How many copies of chromosomes do body cells usually have?
Two
If there are two copies of a chromosome, what does that make the cells?
Diploid cells
Are the two cells created by mitosis identical or not?
Identical
Do the nucleus of each of the two cells contain the same number of chromosomes or not?
They do
What is the process in which body cells divide to produce new cells called?
The Cell Cycle
What is the stage of the Cell Cycle called when the cell actually divides?
Mitosis
What do multicellular organisms use mitosis for?
To grow or replace (damaged) cells
What do some other organisms use mitosis for?
Asexual reproduction
What is the first stage of the Cell Cycle?
Interphase
What happens in Interphase?
The cell grows and increases the number of subcellular structures (mitochondria, ribosomes). After which, it duplicates the DNA, to form a ‘x’-shaped chromosome, where each arm of the chromosome is exactly the same
What is the second stage of the Cell Cycle?
Prophase
What happens in Prophase?
Chromosomes condense, getting shorter and fatter
Membrane around nucleus breaks down, chromosomes lie free in cytoplasm
What is the third stage in the Cell Cycle?
Metaphase
What happens in Metaphase?
Chromosomes line up in the centre of the cell
What is the fourth stage of the Cell Cycle?
Anaphase
What happens in Anaphase?
Spindle fibres pull the chromosomes apart
Chromatids are pulled to opposite ends of the cell
What is the fifth stage of the Cell Cycle?
Telophase
What happens in Telophase?
Membranes form around each set of chromosome
These become the nuclei of the new cell
The nucleus has divided
When does Cytokinesis occur?
Before Telophase ends
What happen in Cytokinesis?
The cytoplasm and cell membrane divide to form two separate cells
What is produced at the end of mitosis?
Two new daughter cells
What are the two genetically identical daughter cells also genetically identical to?
The parent cell
How can you calculate the number of cells produced after multiple divisions?
Use the equation:
Number of cells = 2^n
With (n) being the number of division by mitosis
What is growth?
An increase in size or mass
What is cell differentiation?
The process by which a cell changes to become specialised for its job
Is having specialised cells more effective for multicellular organisms?
Yes, they work more efficiently
What is cell elongation?
A plant cell expands, making the cell bigger and so the plant grows
Does all growth in animals happen by mitosis?
Yes
When is there a faster rate of cell division?
When animals are young
What is most cell division for when animals stop growing?
To repair damaged cells
What is the main way for plants to grow in height?
Cell elongation
Where does cell division usually only happen in plants?
Tips of roots and shoots, in areas called meristems
Do plants grow continuously?
Yes, old trees still grow new branches
Do plants continue to differentiate?
Yes, developing new parts, e.g. leaves, roots
What is cancer a case of?
Uncontrolled cell division
What is the rate of cell division by mitosis controlled by?
Chemical instructions (genes) in an organism’s DNA
What may occur if there is change in one of the genes that controls cell division?
The cell may start dividing uncontrollably, and cause a mass of abnormal cells - a tumour
What does the tumour have to do to be classed as cancerous?
It will start invading and destroying surrounding tissue
What are growth charts used for?
To assess a child’s growth over time
What can growth charts highlight?
Problems such as: obesity, malnutrition, dwarfism
What three measurements are taken when regularly monitoring a baby?
Length, mass and head circumference
Why are doctors likely to investigate?
If a baby is above the top percentile line, if they are below the bottom line, or if there is an inconsistent pattern, like increasing or decreasing by two percentiles
What can stem cells do?
They can differentiate into different types of cells
What are undifferentiated cells called?
Stem cells
What do embryonic stem cells have the potential to do?
Divide and produce any type of cell at all
What are stem cells really important for?
Growth and development of organisms
Do adults also have stem cells?
Yes, but they are only found in certain areas, like in bone marrow
Are adult stem cells as versatile as embryonic stem cells?
No, they can’t produce any type of cell, only certain ones
What do adult stem cells produce?
Replacement cells for damaged ones, like new skin/blood cells
What do meristems of plants contain?
Plant stem cells
Where are the cells in plant that divide by mitosis found?
In the meristem
What do meristems cells act like?
Embryonic stem cells, however these can divide and differentiate as long as the plant lives
What do the unspecialised cells go on to form
Specialised tissues, like the xylem and phloem
What can stem cells be used in?
Medicine
What do doctors use adult stem cells for?
To cure some disease, e.g. sickle cell anaemia
What have scientists started to experiment with?
Extracting stem cells from embryos
Why are scientists trying to extract embryonic stem cells?
To try to stimulate them into differentiating into different specialised cells
What could these embryonic stem cells be used for?
They could be transplanted into someone with damaged cells due to disease or injury, like new cardiac muscle cells could be transplanted into someone with heart disease
What kind of risks are there for procedures surrounding embryonic stem cell transplant?
Tumour development - stem cells divide quickly, if not controlled a tumour could form
Disease transmission - viruses could be transmitted from the cells into the patient
Rejection - if the stem cells aren’t grown using the patients stem cells, the body may see them as foreign and so cause an immune response, more susceptible to disease
What other issues are raised with using embryonic stem cells?
Ethical issues, some see the embryos used in research to be potential human life, whereas some people believe curing patients of suffering is more important than the potential life of the embryos
What do the brain and spinal cord make up?
The Central Nervous System (CNS)
What is the spinal cord a long cord of?
Neurones (nerve cells) that run from the base of the brain down the spine
What does the spinal cord do?
It relays information between the brain and rest of the body
At several places down the cord, what happens?
The neurones split off and connect to the rest of the body
What is the brain made up of?
Billions of interconnected neurones
What is the cerebrum?
The largest part of the brain
What is the cerebrum divided into?
Two halves called the cerebral hemispheres
What does the right hemisphere control?
Muscles on the left side
What does the left hemisphere control?
Muscles on the left side
What are examples of the things different parts of the cerebrum responsible for?
Movement, intelligence, memory, language and vision
What is the cerebellum responsible for?
Muscle coordination and balance
What does the medulla oblongats control?
Unconscious activities, like breathing and heart rate
What are scanners used to do?
Investigate brain function
What do CT scanners use?
X-rays to produce an image of the brain
What does a CT scan show?
Main structures of the brain, but not the functions of them
If a CT scan shows a diseased or damaged brain where the patient has lost some function, what can be worked out?
The function of that part of the brain can be worked out, e.g. if an area of the brain is damaged and the patient can’t see, then that area is involved with vision
What do PET scanners use?
Radioactive chemicals
What do the radioactive chemicals used in PET scanners show?
They show what parts of brain are active whilst the patient is inside the scanner
What can PET scans be used to investigate?
The structure and function of the brain in real time
Why can PET scans be used to study disorders the can change the brain’s activity?
The scans can show if there are areas in the brain that are unusually inactive/active, which links to disorders that change the brain’s activity
What is an example of a disorder that can change brain’s activity?
Alzheimer’s disease, brain activity in areas are reduced and can show up on a PET scan
What can go wrong with the Central Nervous System (CNS)?
Injuries to the brain or spinal cord, tumour, diseases (like Alzheimer’s or Parkinson’s)
Why is it hard to repair the nervous system?
The neurones in the CNS don’t easily repair themselves and scientists have yet to find a way to repair nervous tissue
If a problem occurs in CNS, it can not be easily accessed, so can be hard to treat
Treatment for problems in the nervous system may lead to permanent damage
What are sensory receptors?
Groups of cells that can detect a change in your environment (a stimulus)
What happens to the stimulus detected by the receptors?
The information is converted to a nervous (electrical) impulse and sent along sensory neurones to the CNS)
