Section 2 - Cells And Control Flashcards
Why do enzymes break down molecules
Many molecules of the food are too big to be passed through the walls of the digestive system. This means the digestive enzymes have to break them down into more soluble and smaller molecules. These then can pass easily through the walls of the digestive system and to be absorbed into the bloodstream. They can pass into cells and be used by the body.
Function of enzymes
- they have special shapes so they can ๐พ๐๐ฉ๐๐ก๐ฎ๐จ๐ ๐ง๐๐๐๐ฉ๐๐ค๐ฃ๐จ.
- ๐ฝ๐ง๐๐๐ ๐จ ๐๐ค๐ฌ๐ฃ big molecules
- some enzymes can ๐ ๐ค๐๐ฃ ๐ข๐ค๐ก๐๐๐ช๐ก๐๐จ ๐ฉ๐ค๐๐๐ฉ๐๐๐ง.
How do enzymes help plants?
Plants store energy in the form of starch- carbohydrates. When the plant needs energy, the enzymes break down the starch into smaller molecules- sugars. This can then be respired to transfer energy to be used by the cells
______ converts carbohydrates into ________
- Carbohydrases
- Simple sugars
What converts proteins into amino acids?
Proteases
________ converts lipids into _________
- Lipases
- Glycerol and fatty acids
What happens when lipids are broken down
The fatty acids will lower the pH of the solution they are in
What are lipids
Fats and oils
Why are proteins, lipids and carbohydrates important to be broken down
They can be used for growth and other life processes
How can carbohydrates be synthesised
Joining simple sugars together
Glycogen synthase
An enzyme that joins together lots of chains of glucose molecules to make glycogen which is a molecule used to store energy in animals
How are proteins synthesised
Joining amino acids together and enzymes catalyse the reactions for this
Diffusion
The net movement of particles from a higher concentration to a lower concentration down the concentration gradient
Concentration gradient
If something moves from an area of a ๐๐๐๐ ๐๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ to a ๐๐ค๐ฌ ๐๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ, it is said that it moves ๐ฟ๐ค๐ฌ๐ฃ the ๐พ๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ ๐๐ง๐๐๐๐๐ฃ๐ฉ if itโs from an area of ๐๐ค๐ฌ to ๐๐๐๐, it is moving ๐๐ฅ the ๐พ๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ ๐๐ง๐๐๐๐๐ฃ๐ฉ
Where does diffusion occur๏ฟผ
It only happens in ๐ก๐๐ฆ๐ช๐๐๐จ and ๐๐๐จ๐๐จ. This is because the ๐ฅ๐๐ง๐ฉ๐๐๐ก๐๐จ in these substances are able to ๐ข๐ค๐ซ๐ ๐๐ง๐๐๐ก๐ฎ ๐๐ฃ๐ ๐ง๐๐ฃ๐๐ค๐ข๐ก๐ฎ
Osmosis
The net movement of water molecules from an area of ๐๐๐๐ ๐ฌ๐๐ฉ๐๐ง ๐๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ to a ๐ก๐ค๐ฌ ๐ฌ๐๐ฉ๐๐ง ๐๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ through a ๐จ๐๐ข๐ ๐ฅ๐๐ง๐ข๐๐๐๐ก๐ ๐ข๐๐ข๐๐ง๐๐ฃ๐. Going ๐๐ค๐ฌ๐ฃ the ๐๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ ๐๐ง๐๐๐๐๐ฃ๐ฉ.
What is a semi permeable (also known as partially permeable) membrane?
A membrane with very ๐จ๐ข๐๐ก๐ก ๐๐ค๐ก๐๐จ in it. This is so only ๐ฉ๐๐ฃ๐ฎ ๐ข๐ค๐ก๐๐๐ช๐ก๐๐จ like water can go through it and bigger molecules canโt.
Which way does the water molecules travel through the membrane in osmosis
The water molecules usually travel both ways as the water molecules move about randomly all the time. However, because there are more water molecules on one side theres a steady net flow of water into the region with fewer water molecules
Active transport
The movement of particles across a membrane from a ๐ก๐ค๐ฌ๐๐ง ๐๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ to a ๐๐๐๐ ๐๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ ๐ช๐จ๐๐ฃ๐ ๐๐ฃ๐๐ง๐๐ฎ. This means it is a ๐ฅ๐๐จ๐จ๐๐ซ๐ process as it uses energy ๐ฉ๐ง๐๐ฃ๐จ๐๐๐ง๐ง๐๐ ๐๐ช๐ง๐๐ฃ๐ ๐ง๐๐จ๐ฅ๐๐ง๐๐ฉ๐๐ค๐ฃ.
How is active transport used in the digestive system
When thereโs a high concentration of nutrients in the gut than the blood. The nutrients diffuse naturally into the blood. However, sometimes there is a lower concentration of nutrients in the gut than in the blood. Active transport allows nutrients to be taken into the blood even though the concentration gradient is the wrong way. This helps us stop starving
What is the aim of investigating osmosis
You have to put ๐ฅ๐ค๐ฉ๐๐ฉ๐ค ๐๐ฎ๐ก๐๐ฃ๐๐๐ง๐จ into different concentrations of ๐จ๐ช๐๐ง๐ค๐จ๐ ๐จ๐ค๐ก๐ช๐ฉ๐๐ค๐ฃ๐จ in order to see what ๐๐๐๐๐๐ฉ different ๐ฌ๐๐ฉ๐๐ง ๐๐ค๐ฃ๐๐๐ฃ๐ฉ๐ง๐๐ฉ๐๐ค๐ฃ๐จ have on them
Steps of the osmosis practical
- Prepare sucrose solutions of different concentrations from pure water to very concentrated
- Cut a potato into 1c, in diameter from the same potato
- Divide the cylinders into groups of 3 and use a mass balance to measure the mass of each group
- Place one group in each solution and leave for at least 40 mins
- Remove the cylinders and pat dry so it moves excess water from the surface and you will get an accurate measurement
- Weigh each group again and record the result.
- The sucrose solution is the only thing you will change in the experiment. The size of the potato must be kept the same or the results will be invalid
How do you find the result of the osmosis investigation
Calculate the Percentage change in mass for each cylinder before and after.
New - original/ original x 100
You then plot a graph and analyse your result.
When the curve crosses the x-axis, that means the fluid inside the cylinders and the sucrose solution have the same water solution (isotonic)
the points below the x-axis, the water concentrating of the sucrose is lower than Iโm the cylinders. This causes the sun lingers to lose water so the mass decreases
The _______ the concentration of the sucrose solution, the __________ the ________________
- Higher
- Lower
- Water concentration
Mitosis
A 1 ๐จ๐ฉ๐๐๐ process for ๐๐จ๐๐ญ๐ช๐๐ก reproduction in order to make 2 ๐๐๐ฃ๐๐ฉ๐๐๐๐ก๐ก๐ฎ ๐๐๐๐ฃ๐ฉ๐๐๐l ๐๐๐ฅ๐ก๐ค๐๐ ๐๐๐ช๐๐๐ฉ๐๐ง cells.
Stages of the cell cycle
- Interphase: the DNA duplicates and is copied and formed into X-shaped chromosomes.
- Prophase: The membrane around the nucleus breaks down and the chromosomes are free in the cytoplasm
- Metaphase: The chromosomes line up in the centre of the cell.
- Anaphase: The spindle fibres pull apart the chromosomes into the opposite side of the cells
- Telophase: membranes form around each of the sets of chromosomes which becomes the nucleus of the 2 cells and the nucleus has divided
- Cytokinesis: the cytoplasm and cell membrane divide and form two genetically identical separate daughter cells.
How do you calculate the number of cells theyโll be after multiple divisions.
Number of cells : 2^n. โnโ is the number of cell divisions
Growth
Growth involves:
-cell division
-differentiation
-elongation
It is an increase in size of mass, and plants and animals need to grow and develop due to:
- cell differentiation
- Cell division
Cell differentiation
A process where a cell changes to become specialised for its job. This makes specialised cells which allows multicellular organisms to work more efficiently
Cell division
When cells are divided to new cells which contain the same genetic information
Cell Elongation
Plants grow by cell elongation. This is where a plant expands which makes the cell bigger and making the plant grow
Growth in animals
All growth in animals are by ๐๐๐ก๐ก ๐๐๐ซ๐๐จ๐๐ค๐ฃ. They usually grow while. Theyโre young and then reach full growth then stop growing. Cells divide at a ๐๐๐จ๐ฉ ๐ง๐๐ฉ๐ however once youโre an ๐๐๐ช๐ก๐ฉ, ๐๐๐ก๐ก๐จ ๐๐๐ซ๐๐๐ to ๐ง๐๐ฅ๐ก๐๐๐ ๐๐๐ข๐๐๐๐ ๐ค๐ง ๐ค๐ก๐ ๐๐๐ก๐ก๐จ meaning ๐๐๐ก๐ก ๐๐๐๐๐๐ง๐๐ฃ๐ฉ๐๐๐ฉ๐๐ค๐ฃ ๐๐จ ๐ก๐ค๐จ๐ฉ ๐๐ฉ ๐๐ฃ ๐๐๐ง๐ก๐ฎ ๐๐๐
Growth in plants
Growth in height is usually due to cell elongation and the cell division usually just happens in the tips of the roots.
Plants usually grow continuously so plants continue to differentiate to develop new parts- leaves and routes
What is cancer
When there is a ๐๐๐๐ฃ๐๐ ๐๐ฃ ๐ค๐ฃ๐ ๐ค๐ ๐ฉ๐๐ ๐๐๐ฃ๐๐จ ๐ฌ๐๐๐๐ ๐๐ค๐ฃ๐ฉ๐ง๐ค๐ก๐จ ๐๐๐ก๐ก ๐๐๐ซ๐๐จ๐๐ค๐ฃ, this causes the ๐๐๐ก๐ก๐จ ๐ฉ๐ค ๐๐๐ซ๐๐๐ ๐ง๐๐ฅ๐๐๐ก๐ฎ causing a mass of abnormal cells making a ๐ฉ๐ช๐ข๐ค๐ง. If the tumor ๐๐ฃ๐ซ๐๐๐๐จ ๐๐ฃ๐ ๐๐๐จ๐ฉ๐ง๐ค๐ฎ๐จ the tissue surrounding it, it will be called ๐๐๐ฃ๐๐๐ง.
Growth charts
Used to asses a childโs growth over time. This is in order for an overall pattern in development would be see. And any problems would be highlighted. This will be plotted into growth charts:
-length
-mass
-head circumference
Stem cells
They can differentiate into any different types of cells. They are also called undifferentiated cells and depending on the instructions theyโre given, stem cells can divide by mitosis to become new cells which then can differentiate
Where are stem cells found in
Early human embryos
Embryonic cells
Embryonic stem cells have the potential to divide and produce any kind of cell at all. If they are removed from the embryo, they will differentiate into any cell type
Osmosis in animal cells
- Hypertonic
- Isotonic
- Hypotonic
Hypertonic solution
- High concentration of solutes and a low concentration of free water. So water will move out of the solute into the free water because of osmosis, causing the red blood cell to crenelate (shrivel up)
Isotonic solution
- Has an equal concentration of solutes to the solution inside a cell
Hypotonic solution
- A hypotonic has a low concentration of solutes and a high concentration of free water, water will move into the solute because of osmosis causing the cell to burst
Osmosis in plant cells
- Plasmolyzed
- Flaccid
- Turgid
Plasmolyzed
Plant cells become Plasmolyzed when free water moves out of the cell down the concentration gradient into the surround hypertonic solution that has a lower free water concentration, causing the plant cell to crenelate
Flaccid
Has an equal concentration of solutes to the solution inside the cell
Turgid
When free water moves into the cell, down the concentration gradient because the surrounding hypotonic solution has higher concentration of free water than inside the cell causing the cell to burst
Diffusion in plant cells
Simple covalent molecules like oxygen and carbon dioxide diffuse into and out of the cells.
Carbon dioxide diffuses into plant leaves through the stomata, down the concentration gradient from an area of high concentration to low concentration because carbon dioxide is being used in the palisade mesophyll cells
Diffusion in animal cells
Simple covalent molecules like oxygen and carbon dioxide diffuse into and out of the cells. Oxygen diffuses into an Amoeba down the concentration gradient from an area of High concentration to an area of low concentration as oxygen is used in respiration so that energy can be released into the cell
Active transport In plants
Minerals are absorbed into the root hair cell by active transport. They move from an area of low concentration to an area of Hugh concentration in the vacuole of the root hair cell passing through the cell membrane using energy and a carrier protein
Active transport in animals
Glucose is absorbed from the small intestine into the capillaries via ciliated epithelial cells. The glucose moves from an area of low concentration to high concentration in the epithelial cell passing through the cell membrane via a carrier protein using energy
Adult stem cells
- Ohio found in certain places like Bone marrow. They can only differentiate into limited stem cells - blood cells
- in animals, adult stem cells are used to replace damaged cells - new skin or blood cells
Meristems
- plants grow through meristems, only way the cells in a plant grow.
- in plants, only cells that divide by mitosis are found in plant tissues called meristems
- meristem tissues is found in the areas of a plant that are growing- tips of the root and shoots.
- produce unspecialised that are able to divide and form any cell type in the plant, they act like embryonic cells, but these cells can divide and differentiate to generate any type of cell for as long as the plant lobes.
- unspecialised cells go on to form specialised tissues like xylem and phloem
How can stem cells be used in medicine
- Doctors use stem cells to cure some diseases
- Extracting stem cells from very early human embryos and growing them. Under certain conditions the stem cells can be stimulated to differentiate into specialised cells
- Use stem cells to create specialised cells to replace those which have been damaged by disease or injury.
How is sickle cell anaemia cured
Bone marrow transplant containing stem cells which produce new blood cells
Tumour development
Stem cells divide very quickly, scientists are unable to control the rate at which the transplanted cells divide inside a patient, a tumour may develop
Disease transmission
- viruses live inside cells.
- if donor stem cells are infected with a virus and this isnโt picked, the virus could be passed on to the recipient making them sicker
How does your body react to a stimulus
- A receptor detects a stimulus which is a change in an environment,
- When the receptor detects a stimulus, the information is converted to a nervous electrical impulse and sent along the sensory neutrons to the CNS.
- The CNS coordinates the response and decided on what to do with the stimulus
- The stimulus then travels through the CNS and along the relay neurone.
- The CNS sends information to an effector (gland or muscle) along the motor neurone
- An effector then responds accordingly- muscle contracts or gland releases hormones
- Your reaction time is the time it takes for you to respond to a stimulus
What is your nervous system made up of
Neurones (nerve cells( which go to all parts of the body)
Receptors
Your body contains a lot of sensory neurones, which are group of cells that can detect a change in the environment
Stimulus
A change in the environment
Sensory neurone
Carries impulses from the receptor cell towards the CNS
Response
The action that occurs due to a stimulus
What is the CNS
Contains brain and the spinal cord
Controls the nervous system
What are the extensions that the cell body of neurones connect to
dendrites and dendrons
- they carry nerve impulses towards the cell body.
Axons
- carry the nerve impulse away from the cell body
Myelin sheaths
Some axons are covered in myelin sheaths which acts as an electrical insulator by speeding up the electrical impulse
Long neurones
Some neurones can be very long
- speeds up the impulse so one long neurone is much quicker than lots of short neurones joined together
Short neurones
Short neurones slow down the impulse as connecting with another neurone slows it down, one long neurones are better than lots of short neurones joined together
Structure of sensory neurone
- one long dendron, carries nerve impulses from receptor cells to the cell body.
- the cell body is located in the middle of the neurone
- short axon which carries nerve impulses from the cell body to CNS
Motor neurone structure
- many short dendrites that carry nerve impulses from cell body to CNS
- one long axon which is surrounded by myelin sheaths which support the impulse by moving fast and not going out of the axon. Axon carries nerve impulses from the cell body to the axon terminal
- Axon terminal carries the nerve impulses brought from the axon from the cell body to the effector cells.
The direction of impulse is from left to right
Structure of the relay motor neurone
- many short dendrites carry nerve impulses from sensory neurone to the cell body
- an axon carries nerve impulses from the cell body to motor neurones
Function of sensory neurone
Carries the nerve impulses towards the CNS
Function of motor neurones
Carries the nerve impulses away from the CNS
Function of relay neurone
Carries nervous impulse within the CNS to a muscle or gland (effectors)
Synapses
It is the connection of 2 neurones - connects neurones
- the nerve signals are transferred by chemicals called neurotransmitters which diffuse across the gap
- the neurotransmitters then set off a new electrical signal in the next neurone.
- the transmission of the nervous impulse is very fast but it slows down as the diffusion of the neurotransmitters across the gap takes time
Neurotransmitters
Chemicals that transfer nerve signals across the gap. They set off a new electrical signal in the next neurone.
How fast is the transmission of the nervous impulse
It is very fast however slows down at the synapse as the diffusion of the neurotransmitters across the gap takes time
Reflexes
Automatic, rapid responses to a stimulus which reduces the chance of being injured
Reflex arc
A passage of information in a reflex from the receptor to the effector.
What do the neurones in the reflex arcs do
- The neurones in the reflex arcs go through the spinal cord or through an unconscious part of the brain.
1. When a stimulus is detected by the receptors, impulses are sent along a sensory neurone to a relay neurone to the CNS.
2. When the impulses reach a synapse between the sensory neurone and the relay neurone, they trigger neurotransmitters to be released. These causes impulses to diffuse across the synapse and to be sent along the relay neurone
3. When the impulses reach a synapse between the relay and motor neurone, the neurotransmitters are triggered to be released, causing the impulses the travel along the motor neurone.
4. The impulses then travel along the motor neurone to the effector- muscle or gland
5. The muscle contracts or the gland secretes hormones
6. As you donโt have time to think about the response, it is quicker than the normal response
How do reflexes protect the eye
- Light receptors in the eye detect bright light and sends messages along the sensory neurone to the brain.
- The message then travels along the relay neurone to the motor neurone which tells the circular muscles in the iris to contract, making the pupil smaller.
Uses of mitosis in organisms
- reproduce
- grow and replace cells
- asexual reproduction
- development of embryos
Advantages and disadvantages of stem cells in medicine
ADVANTAGES:
- treats a wide variety of diseases
- organs developed from a patients own stem cells reduce the risk of organ rejection and waiting for an organ donation
- adult stem cells are used successfully in a variety of treatments
DISADVANTAGES:
- rejection
- stem cells can become infected with a virus and could be transmitted to the patient
- risk of stem cells getting mutations leading them to develop cancer cells
- low numbers of stem cells donor
Why are reflexes quicker than normal response
You donโt have to spend time to think about the response making it quicker than the normal response
How many types of tumours exist
2:
1. Malignant tumours
2. Benign tumours
Malignant tumours
Can invade neighbouring tissues and spread throughout the body in the blood leading to the creation of more secondary tumours
Benign tumours
Stay in a specific part of the body often within a membrane
Why is it important that the daughter cells have the same chromosomes as each other
So it can be used for growth and repair of tissues.
Asexual reproduction
What is growth
An increase in size of number of cells by mitosis
Which zone is nearest to the tip of the root
Zone of cell division
Which zone is where the new cells grow in size
Zone of elongation
Which zone is where the new cells differentiate and become specialised into different types of cells
Zone of differentiation
What is cancer
A group of diseases where changes in cells lead to uncontrolled growth and division of cells
Where does cell differentiation primarily happen
- human embryos
- in plants throughout their lives
Where are stem cells found in
- bone marrow
- plant meristems
- human embryos
What are stem cells
Stem cells are undifferentiated cells that havenโt yet specialised to do a specific function. They can create more stem cells or differentiate (become a different type of body cell) to perform another function.
How could stem cells be used to help diabetes or paralysis
Stem cells can be used to replace damaged cells that cause diabetes or paralysis
Uses for stem cells
- Stem cell treatments
- Therapeutic cloning
Describe the stage of the cell cycle that takes place before mitosis
Interphase occurs before mitosis. This is where extra sub cellular structures are produced.
Chromosomes are replicated so there are 2 sets in the cell
Describe what happens during mitosis
- 2 sets of chromosomes are separated by being pulled to opposite ends of the cell.
2, the nucleus divides into 2. - The cytoplasm and the cell membranes divide this is called cytokinesis
- This then makes 2 genetically identical daughter cells
Which processes involve the production of identical daughter cells
- Asexual reproduction
- Repair
- Growth
How can yeast produce alcohol and carbon dioxide
Yeast can respire anaerobically which is known as fermentation
What does the myelin sheath do
It acts as an electrical insulator speeding up the electrical impulse
What do effectors do
Bring about actions in response to a change in the internal or external environment
How does the CNS respond to a stimuli
Via reflex arc
What initiates signalling processes within the body
Receptors
Rejection
If the transplanted cells arenโt grown using the patients own stem cells, the patients body may recognise the cell as foreign and trigger the immune response to try to get rid of them. The patient can take drugs to suppress this response, but this makes them susceptible to disease
Potential risks of stem cells used in;medicine
Tumour development
Disease transmission
Rejectiin
