biology Flashcards
what are amino acids
-proteins
there is a central carbon atom with 4 chemical groups attached
- hydrogen atom
-amino group
carboxyl group
-variable R group
there are 20 different R groups so there are 20 different amino acids
what are amino acids linked together by
peptide bonds
what are peptide bonds
- when a condensation reaction occurs so water is produced between 2 amino acids
- a dipeptide is formed by two amino acids linked by a peptide bond
- three amino acids form a tripeptide
- many amino acids join to form a polypeptide
what is a protein
a polypeptide with more than 50 amino acids
what is a secondary structure
- formed by polypeptide chains
- the structure is held in shape by hydrogen bonds
- the common shapes include are a-helix and b-pleated sheets
what is a tertiary structure
- a secondary structure that is folded into a 3-dimensional shape
- gives the enzyme the shape of its active site
what is an active site
- the area of the enzyme where the substrate binds
- made of a small number of amino acids to form a specific shape due to the proteins in the secondary and tertiary structure.
- when enzymes catalyse the reaction takes place on the active site of the enzyme
what happens with a substrate and active site
- substrates are converted into products
- the substrate binds to the active site
- specific substrates will bind to a particular enzymes active site
what is a complementary shape
when a substrate is only able to fit into the active site of a specific enzyme
what happens after the reaction in the active site
- the product is released and the active site is available to catalyse another reaction
what are the only ways an active site will not fit into a substrate
- if the temp goes too high, the hydrogen bonds will break
- the enzyme changes shape
- the active site loses its shape
- the enzyme is denatured and is unable to act as a catalyst.
what is the collision theory
- particles must collide
- particles must have enough energy to react
- the energy of the collision depends on the speed of the particle and the angle they collide
- the minimum energy needed for particle to react is the activation energy
when will the activation of the enzyme lower
- when more particles have required energy to react
- there is more successful collisions
- there is a faster reaction
what is catalytic activity
increase in the rate of a reaction caused by the inclusion of an enzyme
what is a substrate
the molecule that is affected by the action of the enzyme
what is denatured
when the tertiary structure of the enzyme is changed
how can you measure the rate of enzyme reaction
-measuring the decrease in substrate
-measuring the increase in the product
measuring the increase in the product is easier as you know the starting measurement for the product will be 0.
the initial rate of reaction must be recorded because the rate will decrease as the substrate is used up and its concentration decreases
what are factors affecting activity of an enzyme
- temperature
- pH
- concentration
how does temperature affect the enzyme
- each enzyme has an optimum temp at which it works fastest
- in humans, it is 40 degrees
- as the temp increases the optimum the rate of reaction increases
- below optimum temperature, there is less energy = fewer collisions = slower reaction
- above optimum temp - hydrogen bonds in enzyme break = hydrogen bonds in enzyme break = enzyme and active site loses its shape (denatured) = no catalysis
how does pH affect the enzyme
- enzymes have an optimum pH
- the pH is between 7 and 8
- pH affects the charge on the active site, if pH changes then the charges on the active site change and the substrate may no longer be able to bind to it.
what does the concentration affect in the enzyme
the concentration of the enzyme and of the substrate affect the rate of reaction
what will the increase in substrate concentration lead to
- increase in the rate of collisions
- increase in rate of reaction
what will the increase in enzyme concentration lead to
- increase in the rate of collisions
- increase in the rate of reaction
what will happen if the concentration of the substrate is too high
- there will be no more active sites for them to bind to.
- this will mean that increasing the concentration of the substrate will no longer affect the rate of reaction
what will happen if the concentration of enzyme is too high
there are too many free available active sites compared to substrate molecule, the rate of reaction will no longer increase
what is diffusion
the movement of molecules down a concentration gradient in a semi-permeable membrane from a region of high to low concentration. diffusion is passive so it doesnt require an input of energy
how does the dye and water experiment relate to diffusion
- when the dye molecules are added they move from a high concentration to areas of low concentration until the dye molecules has been equally spread
- the molecules are in dynamic equalibrium
what will happen if more dye molecules are added
the faster the rate of speed because there is a bigger concentration gradient.
what are the factors affecting the rate of diffusion
- size
- temperature
- distance through a substance
- surface area
- shape of the surface of which molecule is diffusing
how does size affect the rate of diffusion
larger molecules move slowly compared to smaller ones, the rate of reaction decreases
how does the temperature affect the rate of diffusion
a higher temperature increases the energy molecules have so they move faster, increasing the rate of diffusion
how does the distance through a substance affect the rate of diffusion
the greater the distance that the molecules must travel through a substance, the slower the rate of diffusion. eg leaves are thin which reduces the distance that gases diffuse through and so increases the rate of diffusion
how does the surface area affect the rate of diffusion
as the surface area increases, the area of which molecules can spread is increased and so the rate of diffusion increases
how does the shape of the surface of which the molecule is diffusing affect the rate of diffusion
the shape of the surface of which the molecule is diffusing can affect the rate of different, the shape of a cell can affect its surface area, therefore affecting the rate of diffusion of molecules into or out of the cell
what is the arrangement of particles in a solid
close together
regular pattern
what is the movement of particles in a solid
vibrate about in a fixed position
what is the arrangement of particles in a liquid
close together
random
what is the movement of particles in a liquid
move around each other
what is the arrangement of particles in a gas
far apart
random
what is the movement of particles in a gas
move quickly in any direction
what are the properties of a solid
fixed shape
cannot flow
cannot be compressed or squashed
what are the properties of a liquid
take shape of a container
they flow and move randomly
cannot be compressed or squashed
what are the properties of a gas
completely fill container
they flow and move randomly
can be compressed or squashed
what two states of matter allow diffusion and why
gas and liquids as they can flow and move randomly, allowing diffusion in gases and liquids
what are the human effects on plant growth
- correct soil pH
- optimum watering
- correct nutrients present
what are the negative human effects on plant growth
trampling
picking wildflowers
removing hedges/trees
what is the pH of the soil that plants grow the best at
plants grow best in a soil with pH between 4.5 and 7.5
how can an acidic soil affect the plant growth
there is a deficiency in necessary minerals, such as iron and manganese
how does soil aeration affect the plant growth
to allow sufficient oxygen to get to the plant and for carbon dioxide to be removed
what is formed in the plant when there is little aeration
toxins such as hydrogen sulfide gas
how does the temperature affect plant growth
most plants have an optimum temperature they will grow at
temperature is important in seed germination as seeds need the soil to be within a specific temperature range in order for them to germinate
how does light intensity affect plant growth
- plants need light for photosynthesis
- plants in high light intensity are likely to have better growth than those in the shade
- plants used to low light intensity can get sub scored in the sun
- different plants prefer different light intensity and many prefer to be in the shade at some point of the day
- leaves in the shade may grow larger in order to absorb more light. other differences can be noticed also, difference in colour
how can the soil moisture affect plant growth
if there is isn’t enough soil moisture:
- the rate of photosynthesis decreases
- plants cannot take up necessary minerals and nutrients
how can little rainfall affect plant growth
- yellow leaves
- dry leaves
- ground cracked
how can too much rainfall affect plant growth
- yellow leaves
- rotted roots
- minerals/nutrients washed away
- soil erosion
what happens to the plant in distilled water
hardly any growth
what happens to the plant with no nitrogen ions
very little growth
what happens to the plant with no iron
yellowish leaves
what happens to the plant with no magnesium
poor growth and yellowish leaves
what happens to a plant with no potassium
weak shoots and roots
what happens when a plant is full of nutrients
healthy growth
what is random sampling
each potential sample has the same probability of being chosen
when will you use random sampling
area under study is large
area under study is fairly uniform
there is limited time
what are abiotic factors
soil type/ moisture/ pH
topography
weather/sunlight
temperature
what are quadrats
- a small area of habitat, which usually has a grid within it -the frame is placed on the ground
- the plants inside the quadrat are counted
how do you place a quadrat
they must be placed randomly to get a representative sample
- draw a map of the area
- overlay a grid on the map
- use a random number generator to decide where the quadrat is placed
what is a line transect
-sampling lines are set up across the area to be sampled.
-species can be recorded along the whole length of the line - this continuous sampling
or species are recorded at set intervals along the line - this is systematic sampling
what is a belt transect
- gives informaton on the abundance of species
- quadrats are placed at set intervals
