Flashcards in Biology Deck (97):
What is an organelle
A structure which Carrie sour a certain function in a cell
What is the function of a cell wall and where is it found
It supports, strengthens and maintains the shape of the cells and is found in bacterial, fungal and plant cells
What is the function of a mitochondria and where is it found
It is the site of aerobic respiration in the cell and is found in plant, animal and fungi cells
What is the function of chloroplasts and where can they be found
Site of photosynthesis and is found in some plant cells
What is the function of the cell membrane and where is it found
To control entry and exit of substances and is found in plant, bacterial, fungi and animal cells
What is the function of the sap vacuole and where is it found
Stores water, sugar and salts and can be found in plant cells
What is the function of the nucleus and where can it be found
Controls the cell’s activities and stores it’s genetic information. Can be found in plant, fungi and animal cells
What is the function of the ribosomes and where are they found
Site of protein synthesis and are found in plant, animal,fungi and bacterial cells
What is the function of plasmids and where are they found
They code for a few proteins and are only found in bacterial cells as they have no nucleus
What is the function of the cytoplasm and where is it found
Site of all biochemical reactions and found in animal, plant, bacterial and fungi cells.
What is unique about plant cell walls
They are made of cellulose compared to other cells which have membranes made of other materials.
What is the structure of a cell membrane and what does this mean
Constantly moving Phospholipid bilayer with proteins which allow some substances to pass through with ease, making it selectively permeable
What is passive transport
The movement of molecules or ions down a concentration gradient from an area of high to low concentration. No energy input is required. Diffusion is an example of passive transport
What is osmosis
The movement of molecules down a concentration gradient from a high to low concentration through a selectively permeable membrane. Doesn’t require energy input
What is the effect of osmosis on a typical animal cell
It will shrink or burst depending on the inner and outer concentrations. This happens as they have no cell wall to prevent them from bursting.
Burst if higher concentration outside
Shrink if higher concentration inside
What is the effect of osmosis on a typical plant cell
It will become turgid or plasmolysed as it has a cell wall to prevent it from bursting
Plasmolysed if higher concentration inside
Turgid if higher concentration
What is active transport
The movement of molecules or ions up a concentration gradient from a low to higher concentration. Energy input is required in the form of ATP. Cells which use active transport have many mitochondria due to this.
What is DNA
DNA is a molecule found in all living cells, in the nucleus in plant, animal and fungi cells but in ring-like structures called plasmids in bacterial cells.
What is the purpose of DNA
Contains genetic information our body needs to produce proteins, which then decide your physics, characteristics.
What is the structure of DNA
A doubled stranded helix, with two sugar-phosphate backbones that curve around each other and are held together by complementary base pairs.
What are the variables in DNA
The four bases are: adenine, thymine, guanine and cytosine. (A,T,G,C)
They pair together as: A-T
What does the order of bases determine
Sequence of amino acids which then codes for a specific protein.
What is mRNA
A molecule that makes a complementary copy of a strand of DNA and then takes it too the ribosome as the DNA molecule is too large to leave the nucleus.
What happens in the ribosomes once the mRNA has arrived
The base sequence codes for amino acids - three bases codes for one amino acid - the sequence of these acids then codes for the particular protein, depending on how the chain of acids fold (polypeptide chain).
What functions do proteins have
What are antibodies and what do they do
They are a type of protein which provides your body defence against bacteria and viruses by binding to them so that white blood cells can recognise and destroy them
What are receptors and what do they do
They are a type of protein which allows cell to recognise specific chemical signals
What are hormones and what do they do
They are a type of protein which is used as a chemical messenger which is transported in the blood.
What do structural proteins do
They provide strength and support for cell structures
What are enzymes and they’re key characteristics
Made in all living cells
Speed up chemical reaction within a cell
Unchanged in the process so can be reused
What is enzyme specificity
The fact that only one substrate works with a specific substrate.
Why are enzymes specific to one substrate
As they have complementary active sites - where enzymes bind to substrates - which are specific to only one another.
An example of an enzyme reaction is
Hydrogen peroxide —-catalase—-> oxygen + water
What are the two main types enzyme controlled reactions
Degradation- when one substance is broken down into two or more.
Synthesis- when two or more substances are bound together to form one substance
An example of a synthesis reaction is
An example of a degradation reaction is
What is optimum temperature and the effect of too Hugh temperatures on an enzyme.
Optimum temperature is the temperature at which an enzyme work the fastest.
Too high temperatures denatures the protein changing the shape of it meaning it is no longer complementary to its substrate
What is an enzymes optimum pH and what happens when it isn’t in its optimum range
An enzymes optimum pH is the pH at which it works the fastest.
If it isn’t in its pH range it will become denatured and will no longer be complementary to its substrate i.e. too high or too low pH.
What can denaturing be described as
What is genetic engineering
The artificial transfer of genetic information from one cell to another
What is genetic engineering controlled by
What is the first stage of genetic engineering
The desired gene is identified in the source cell or chromosome
What is the second stage of genetic engineering
The required gene is extracted from the DNA using enzyme ‘scissors’
What is the third stage of genetic engineering
The plasmid from the target bacterial cell is extracted
What is the fourth stage of genetic engineering
The required gene is inserted into the extracted plasmid by cutting out a section of the plasmid using enzyme ‘scissors’
What is the fifth stage of genetic engineering
Replace the modified plasmid into the target cell and grow it in ideal conditions so that it reproduces. Then the required gene can be gathered and extracted in mass.
What is respiration
The process by which energy is released through the breakdown of glucose in substances. It is enzyme controlled.
What is the general formula of respiration
Glucose —-enzymes—-> waste products + energy
What is released with the waste products due to respiration
Energy in the form of ATP, which can then be used as an immediate source of energy.
What cellular activités require energy input in the form of ATP
Muscle cell contraction
Transmission of nerve impulses
What must be present for aerobic respiration to occur and where does aerobic respiration occur.
What is the first stage of aerobic respiration
The breakdown of glucose into two molecules of pyruvate.
2 molecules of ATP are also produced in the reaction from 2ADP + 2Pi
Occurs in cytoplasm
Doesn’t require oxygen
What is the second stage of aerobic respiration
The breakdown of two molecules of oyruvate into carbon dioxide and water. 36 molecules of ATP are also produced from 36ADP + 36Pi
Occurs in mitochondria
Oxygen is present/needed.
How many molecules are produced in aerobic respiration overall
What is fermentation
The breakdown of glucose without oxygen
What happens in fermentation
Glucose is broken into pyruvate, producing 2ATP molecules in the process from 2ADP + 2Pi.
Occurs in cytoplasm
No oxygen required
What is pyruvate converted into in plant cells during fermentation
Ethanol and carbon dioxide
What is pyruvate converted into in animal cells, during fermentation
Lactate (lactic acid)
What can be concluded of fermentation against aerobic respiration
Fermentation is much less efficient than aerobic respiration as it produces much less energy.
What can the conversion of pyruvate into lactate or carbon dioxide and ethanol, during fermentation be known as
An irreversible reaction
What is the importance of cell division in multicellular organisms
Repair of damaged cells
Replace dead cells
What is the importance of cell division in unicellular organisms
What is the centre of a chromosome called
What are the two separate strands that make up chromosomes called
What is mitosis
The production of new body cells by cell division
What is the first stage of mitosis
The chromosomes coil up and condense and then appear as two identical chromatids held together by a centromere.
What is the second stage of mitosis
The chromosomes line up at the equator of the cell and the spindle fibres begin to form from the opposite poles of the cell.
The nuclear membrane also breaks down.
What is the third stage of mitosis
The chromatids are then pulled apart by the spindle fibres and pulled to opposite poles of the cell.
What is the fourth stage of mitosis
The cytoplasm divides leaving two separate cells.
Now called chromosomes again
2 daughter cells
Genetically identical as no genetic information is lost
Nuclear membrane and cell membrane reform
What does mitosis do
Maintains the chromosome complement (46 in humans, 23pairs). This means that I generic information is lost.
Stem cells are...
Undifferentiated cell’s which divide for either:
- self renewal
Two types of stem cells are...
What can embryonic stem cells do..
Produce all the cells in your body regardless of what type they already are.
What can tissue stem cells do..
They produce a limited number of cell types. For example blood stem cells can only make other types of cell in your blood.
What are some ethical issues with stem cells
Destroys embryos and potential human life
Red blood cells have...
+ bi-concave shape
+ increases surface area, more space for oxygen and haemoglobin
+ full of haemoglobin to carry oxygen
+ no nucleus so more space for oxygen
Root hair cells have...
+ a large surface area
+ allows more water and nutrients to be absorbed by the cell, allowing the hair to grow
What is the sequence of organisation in humans
Cell-> tissue-> organ -> organ system -> organisms
What are tissues
A group of cells
What are organs
A group of tissues
What are organ systems
A group of organs
What are organisms
A group of organ systems
What is the CNS made up of
What does the CNS do
Processes information from the senses
Send impulses to bring about a response
The flow of information goes
Stimulus-> receptors-> sensory neurone-> CNS-> motor neurone-> effectors-> response
A reflex arc is...
An internal system to prevent the body from harming itself. It goes through the same process as the previous card but instead of going to the brain it only goes to the spinal cord which makes it quicker
What is a synapse
A gap between two neurons which is crossed by the triggering of chemical which diffuse across the gap and trigger the next impulse.
What is the function of the cerebrum and where is it
Center of: conscious thought
Located at the top section of the brain
What is the function of the cerebellum and where is it located
Controls balance and coordination of movement. It is at the bottom right of the brain
What is the function of the medulla and where is it located
Controls heart and breathing rate.
Located at the bottom of the brain and looks like a tube
What is the function of the pituary gland and where is it located
Releases hormone and is situated at the bottom left of the brain
How could hormones be described
Specific to their substrate as they are complementary to each other at their binding site.
What happens if blood glucose is too high or low
What happens if you have type 1 diabetes
Your body doesn’t produce insulin and you must therefore inject insulin into your blood stream.
What happens if you have type 2 diabetes
Your body cells no longer responds to insulin and you must therefore control your diet and exercise.
If blood glucose is too high...
Liver coverts glucose to glycogen
Blood sugar falls