Cells - questions Flashcards
Role of enzymes
Biological catalysts which speed up biochemical reactions in an organism.
Description of the structure of enzymes including term active site
Enzymes are proteins made up of amino acids linked together in one or more polypeptide chains. Enzymes have an active site that joins with a specific substrate
Explain why the shape of the enzyme active site is needed for a reaction to occur
The shape of the active site is critical as is the part of the active site that enable it to bind to a single type of substrate, so that the enzyme is able to continue to catalyse reactions
Describes inhibitors effect on enzyme
Inhibitors are compounds which modify the catalytic properties of the enzyme and, therefore, slow down the reaction rate, or in some cases, even stop the reaction
Describes the function of the cell cycle
The function of the cell cycle is to duplicate DNA in the chromosomes and then segregate the copies into two genetically identical daughter cells
Describes how one of the stages of the cells is involved
During the G1 stage the cell increases in size, in the S stage the cell copies its DNA, the cell prepares to divide during the G2 stage, and it divides during mitosis
Give equation for photosynthesis
carbon dioxide + water → glucose + oxygen (in the presence of light and chlorophyll)
Describe the purpose of photosynthesis
Photosynthesis is the process of plants using sunlight, water, and carbon dioxide to produce glucose and oxygen
Describe light dependent phase
Light energy is absorbed by the pigment chlorophyll. This light energy splits the water molecule into oxygen and hydrogen. Hydrogen ‘goes to the’ light-independent process, while oxygen is excreted as a waste product (via stomata on leaves).
Describe light independent phase
In the light independent phase, carbon dioxide and Hydrogen are joined together to create glucose. This phase does not require light
Describes how water availability affects rate of photosynthesis
Because water is a reactant in the light dependent phase, water availability can affect rates of photosynthesis as there is less hydrogen. This means that the light independent phase will not be able to happen and glucose will not be created.
Define osmosis
the movement of water across the membrane from an area of higher water concentration to lower water concentration.
Give equation for aerobic respiration
glucose + oxygen → 36ATP + carbon dioxide + water
Describe the purpose of respiration
to provide oxygen to the cells at a rate adequate to satisfy their metabolic needs
Draw and label mitochondria
refer to diagram
Describe an adaptation of the mitochondria
Mitochondria have a double membrane structure, with an inner layer with many folds to create a high surface area. This provides more space for more metabolising proteins and therefor they are able to create more energy at one time.
State a cell function that requires energy
Active transport requires energy to move molecules from an area of low concentration to an area of high concentration
Define diffusion
The movement of materials from an area of high concentration to an area of low concentration
Define facilitated diffusion
A form of passive transport where molecules move across the cell membrane through the membrane proteins
Define active transport
The movement of molecules from an area of low concentration to an area of high which requires energy
What are factors that affect enzymes
Enzymes are affected by pH and temperature.
A low or high pH will disrupt the hydrogen bonds of the enzyme’s protein and cause the enzyme to denature. This means the active site will change shape and not fit with the specific substrate.
At very low temperatures the enzyme action is slow and at high temperatures the enzyme may become denatured which makes their active site change shape and not fit with its specific subsrate.
Define anaerobic respiration
Anaerobic respiration occurs in the cytoplasm of the cell. It does not require oxygen. In most cases, during anaerobic respiration, glucose is broken down into carbon dioxide or ethanol.
Define chloroplast
A chloroplast is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells
Relate structure of chloroplast to efficient photosynthesis
Part of the photosynthesis reactions occur in an internal membrane within the organelle. The chloroplast contains many of these internal membranes, making photosynthesis very efficient
Describe DNA replication
DNA replication is the process by which the genome’s DNA is copied in cells. Before a cell divides, it must first copy (or replicate) its entire genome so that each resulting daughter cell ends up with its own complete genome.
Explain why DNA replication is necessary for cell cycle
DNA replication ensures that each daughter cell gets a copy of the genome, and therefore, successful inheritance of genetic traits
Define mitosis
The purpose of mitosis is to produce two identical cells for
growth of the organisms AND the repair of tissues / replacement of cells.
Explain why mitosis is necessary for cell cycle
after a cell reaches a certain size, it must carry out mitosis to produce two new
smaller cells that have a larger surface area:volume ratio and can transport materials at a
fast-enough rate to support cellular function.
