Cell Biology Flashcards
What are the types of cells
Eukaryotic (animal and plant cells) or Prokaryotic (bacterial cells)
What sub cellular structure do plant cells have that animal cells don’t have
Cell wall, permanent vacuole, chloroplasts
what is the function of the nucleus
Contains genetic material that controls the activities of the cell
What is the function of the cytoplasm
Where most chemical reactions happen (contains enzymes)
What is the function of the cell membrane
Holds the cell together and controls what goes in and out
What is the function of the mitochondria
Where most reactions for aerobic respiration take place (respiration transfers energy that the cell needs to work)
What is the function of the ribosomes
Where proteins are made in the cell
A plant cell has a rigid cell wall, what is the function of a cell wall
Supports the cell and strengthens it (made of cellulose)
What is the function of a permanent vacuole in a plant cell
Contains cell sap, a weak solution of sugar and salts
What is the function of chloroplasts in a plant cell
Where photosynthesis occurs (which makes food for a plant), contain green substance called chlorophyll which absorbs the light needed for photosynthesis
What is the difference between plant/animal cells and bacterial cells
Bacteria cells don’t have chloroplasts or mitochondria, they don’t have a ‘true’ nucleus- instead they have a single circular strand of dna that floats freely in the cytoplasm, they may also contain one or more small rings of dna called plasmids
What is the function of a microscope
They allow us to see things which we can’t see with the naked eye
What is the function of a light microscope
They use light and lenses to form an image of a specimen and magnify it, they let us see individual cells and large sub cellular structures (eg nuclei)
What is the function of an electron microscope
They use electrons instead of light to form an image, they have a much higher magnification than light microscopes, they also have a higher resolution (the ability to distinguish between two points), they allow us to see much smaller things in more detail (eg the internal structure of mitochondria)
How can you calculate the magnification of an image
Use the formula:
Magnification= image size (divided by) real size
How do you use a light microscope (practical)
What is differentiation
The process which a cell changes to become specialized for its function, they may develop different sub cellular structures or turn into different types of sells so they can carry out specific functions
What are the examples of specialized cells
Sperm cells, nerve cells, muscle cells, root hair cells. Phloem and xylem cells
What is the function of a sperm cell which is specialized for reproduction
To get the male dna to the female dna, it has a long tail and a streamlined head to help it swim, lots of mitochondria in the cells to provide energy, also carries enzymes to digest through the eggs cell membrane
What is the function of nerve cells which are specialized for rapid signalling
To carry electrical signals from one part of the body to another, long to cover more distances and have branched connections to connect to other cells and form a network
What is the function of a muscle cell specialized for contraction
To contract quickly, long and contain lots of mitochondria to generate energy for contraction
What is the function of a muscle cell
What is the function of a root hair cell specialized for absorbing water and minerals
Root hair cells are cells on the surface of plant roots which grow into long hairs that stick out into the soil, that gives the plant a large surface area for absorption of water and mineral ions from the soil
What is the function of phloem and xylem cells which are specialized for transporting substances
They form tubes which transport substances such as food and water around plants, to form tubes the cells are long and joined end to end, xylem cells are hallow in the Centre and phloem cells have very few sub cellular structures so stuff can flow through them
How many pairs of chromosomes from a human cell
23 pairs
What are body cells
They normal have two copies of each chromosome- one from the ‘mother’ and one from the ‘father’ so humans have two copies of chromosome 1 etc.
What does each chromosome carry
A large number of genes, different genes control the development of different characteristics eg) hair colour
What is the cell cycle
Makes new cells for growth, development and repair
What are the two main stages of the cell cycle
Growth & dna replication and mitosis
Why do multicellular organisms use mitosis
To grow or replace cells that have been damaged
What is the process of growth & dna replication
1) in a cell that’s not dividing the dna is all spread out in long strings
2) before it divides the cell has to grow and increase the amount of sub cellular structures such as mitochondria and ribosomes
3) it then duplicates the dna- so there’s one copy of each new cell- the dna is copied and forms X shaped chromosomes
One it’s contents and dna have been copied the cell is ready for mitosis
What is the process of mitosis which continues from growth & dna replication
4) the chromosomes line up at the centre of the cell and cell fibres pull them apart
5) membranes form around each of the sets of chromosomes, these become the nuclei of the two new cells
6) lastly the cytoplasm and cell membrane divide
The cell has now produced the new daughter cells (identical)
what can embryonic stem cells turn into
Any type of cell
What is differentiation
The process by which a cell changes to become specialised for its job
What are undifferentiated cells (stem cells)
(Stem cells) can divide to produce lost more undifferentiated cells, they can differentiate into different types of cell depending on what instructions they’re given
Where are stem cells found
In early human embryos- potential to turn into any kind of cell
Where are adult stem cells found
Bone marrow
How can adult stem cells be used to cure diseases
Stem cells transferred from the bone marrow of a healthy person can replace faulty blood cells in the patients who receives them
How can embryonic stem cells be used to replace faulty cells in sick people
You could make insulin producing cells for people with diabetes or nerve cells for people paralysed by spinal injuries
How is therapeutic cloning beneficial for a patient
And embryo could have the same genetic information as the patient so the stems cells would have the same genes so less chance of rejection from the patient’s body
What are the risks involved with using stem cells for medicine
Stem cells grown in a lab could become contaminated with a virus which would be passed on to the patient and make them sicker
What are the risks involved with using stem cells for medicine
Stem cells grown in a lab could become contaminated with a virus which would be passed on to the patient and make them sicker
Why are some people against stem cell research
They feel that human embryos shouldn’t be used for experiments since each one is a potential human life, others think that curing existing patients who are suffering is more important than the rights of embryos
I’m plants where are the stem cells found
Meristems (parts of the plant where growth occurs)
I’m plants where are the stem cells found
Meristems
What is diffusion
The gradual movement of particles from an area of higher concentration to lower concentration
When does the diffusion rate increase
When the concentration gradient is larger And a higher temperature will also give a faster diffusion rate (particles have more energy)
What is osmosis (a special case of diffusion)
Osmosis is the movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
How can you observe the effects of sugar solutions on plant tissue
1) cut up potato into identical cylinders, get some beakers with different sugar solutions (pure water and very concentrated sugar solution with a few other concentrations in between)
2) measure the mass of the cylinders, leave one in each beaker for 24hours
3)take out, dry, measure mass again
4)if the cylinders have drawn in water by osmosis they will have increased in mass but if water has been drawn out they will have decreased in mass, you can calculate the percentage change in mass
What is the dependent variable in the osmosis practical
Chip mass
What is the independent variable in the osmosis practical
Concentration of the sugar solution
What is the control variable in the osmosis practical
Temperature, time, volume of solution
What is active transport
When substances need to be absorbed against a concentration gradient
Root hair cells take in minerals using active transport
Active transport allows the plant to absorb minerals from a very dilute solution against concentration gradient, essential for growth, but active transport need’s energy from respiration to make it work
When is active transport used in humans
In the gut when there is a lower concentration of nutrients in the gut but a higher concentration of nutrients in the blood
What is exchange surfaces
How easily stuff moves between an organism and its environment but it depends on its surface area to volume ratio
How does gas exchange happen in the lungs
Transfer oxygen to the blood and remove waste carbon dioxide (gas exchange)
How are alveoli specialised to maximise diffusion of 02 and CO2
Enormous surface area, moist lining for dissolving gases, thin walls, good blood supply
How are villi adapted to provide really big surface area
A single layer of surface cells, good blood supply to assist quick absorption
