Nat 5 - Cell Biology Flashcards
What is the function of the cell wall?
To support the cell
What is the function of the mitochondria?
Site of aerobic respiration
What is the function of the chloroplast?
Site of photosynthesis
What is the function of the cell membrane?
Controls what substances pass into and out of the cell
What is the function of the cytoplasm?
Site of most chemical reactions
What is the function of the vacuole?
Contains cell sap and regulates water content by osmosis
What is the function of the nucleus?
Controls cell activities
What is the function of the ribosome?
Site of protein synthesis
What is the function of the plasmid?
Controls cell activities in bacterial cells
Name the two components of the cell membrane
Proteins and phospholipids
Define the term passive transport
Transport that does not require energy e.g. Diffusion and osmosis
Define the term diffusion
The movement of molecules from an area of a high concentration to an area of a low concentration down a concentration gradient until evenly spread
Name the membrane protein involved in diffusion
Protein channel
Name three raw materials that would diffuse into cells
Oxygen, glucose and amino acids
Name one waste product that would diffuse out of cells
Carbon dioxide
State the importance of diffusion in living cells
It is the process by which useful molecules enter and waste products are removed
Define the term osmosis
The movement of water molecules from a high water concentration to a low water concentration across a selectively permeable membrane
Name the membrane protein involved in osmosis
Protein channel
Describe what happens to an animal cell in pure water
Water moves in from a HWC to a LWC and the cell swells and bursts
Describe what happens to an animal cell in a strong salt solution
Water moves out from a HWC to a LWC and the cell shrinks
Describe what happens to a plant cell in pure water
Water moves in from a HWC to a LWC and the cell becomes turgid
Describe what happens to a plant cell in a strong salt solution
Water moves out from a HWC to a LWC and the cell becomes plasmolysed
Define the term active transport
The movement of ions or molecules from a low concentration to a high concentration against a concentration gradient
Name the membrane protein involved in active transport
Protein pump
Describe the importance of mitosis
It is essential for growth and repair
Define the term diploid
Containing two sets of chromosomes
Describe stage one of mitosis
Chromosomes in the nucleus become visible
Describe stage two of mitosis
Chromosomes replicate to become two identical chromatids
Describe stage three of mitosis
Chromosomes line up along the equator of the cell
Describe stage four of mitosis
Spindle fibres pull chromatids to opposite poles of the cells
Describe stage five of mitosis
Two new nuclei form and cytoplasm splits
Describe stage six of mitosis
Two daughter cells are formed, identical to mother cells
Define the term chromatid
Each of the two thread-like strands which a chromosome divides into during mitosis
Define the term equator
The line across the centre of the cell
Describe the role of the spindle fibres
They pull chromatids to opposite poles of the cell
Explain how mitosis maintains the diploid chromosomes complement
The number of chromosomes in the nucleus are doubled and then divided between the nuclei of the two daughter cells produced. This ensures that the diploid chromosome complement is maintained
Explain why aseptic technique must be used when culturing cells
To prevent contamination from unwanted bacteria and micro organisms
Name two types of growth medium
Nutrient agar and liquid broth
Name three factors that must be controlled when culturing cells
Temperature, oxygen concentration and pH
State what molecule DNA codes for
Proteins
Describe the structure of a DNA molecule
DNA molecules consist of two strands twisted together to form a spiral known as a double helix. Each strand is made up of many smaller units called nucleotides. They also have complementary base pairs.
Describe the complementary base pairs in DNA
There are four DNA bases - adenine, thymine, guanine and cytosine. Each base’s molecular structure can only fit one other type of base - A fits T and G fits C
State what determines the amino acid sequence of a protein
The order of the bases
State where mRNA is formed in the cell
Nucleus
Describe the role of mRNA in the production of proteins
It carries a complementary code from the DNA in the nucleus to the ribosomes
State where the protein is assembled in the cell
Ribosomes
State what determines the shape and function of a protein
The sequence of amino acids
State five functions of proteins in the cell
Structural, hormones, enzymes, antibodies and receptors
Define the term enzyme
A biological catalyst
State two properties of enzymes
They speed up chemical reactions and are unchanged by a reaction
Describe the role of the active site in enzyme action
The active site is complementary to a specific substrate and fits with that substrate in enzyme action
Define the term substrate
The molecule that an enzyme works on
Define the term product
The molecule that results from enzyme action
Describe a degradation reaction with an example
When large molecules are broken down into smaller molecules e.g.
Describe a synthesis reaction with an example
When smaller molecules are built up into larger molecules e.g.
State two factors that affect enzyme activity
Temperature and pH
Define the term optimum
The condition at which an enzyme works best
Define the term denatured
The change of shape of an enzymes active site due to high temperatures
Explain why an enzyme becoming denatured affects the rate of reaction
The active site loses its shape and the enzyme can no longer fit with their specific substrate
Define the term genetic engineering
The process by which DNA is transferred from one organism to another
State two types of cells that can transfer DNA naturally
Bacterial cells and viruses
Name the organism used in genetic engineering and the structure extracted from this organism
Animals
Chromosome is extracted
Describe stage one of genetic engineering
The chromosome in the human cell is identified
Describe stage two of genetic engineering
The required gene is removed from the human chromosome using enzymes
Describe stage three of genetic engineering
The plasmid is identified in the bacterial
Describe stage four of genetic engineering
The plasmid is removed from the bacterial cell and cut open with enzymes
Describe stage five of genetic engineering
The gene is sealed into the plasmid
Describe stage six of genetic engineering
The plasmid with the human gene is inserted back into the bacterial cell
Describe stage seven of genetic engineering
The bacterial cell containing the plasmid with the human gene is grown
Describe stage eight of genetic engineering
The product is extracted from bacterial cells
Describe the role of enzymes in genetic engineering
They are used to cut pieces of DNA from one organism and put it into the gap in the DNA of another organism
Define the term photosynthesis
The process by which plants make their own chemical food using light energy from the sun
State the word equation for photosynthesis
Carbon dioxide + water - light energy/chlorophyll - sugar + oxygen
Name stage one of photosynthesis
Light dependent stage
Name the pigment that traps light energy
Chlorophyll
Describe the energy change that takes place in stage one of photosynthesis
Light energy is converted into chemical energy in the form of ATP
Describe what happens to water molecules in stage one of photosynthesis
Water molecules are broken down into oxygen and hydrogen
State which products from stage one of photosynthesis are required for stage two of photosynthesis
Hydrogen and ATP
Name the by-product of stage one of photosynthesis
Oxygen
Name stage two of photosynthesis
Carbon fixation stage
State what controls stage two of photosynthesis
Enzymes
State what is combined with the products from stage one to produce sugar in stage two of photosynthesis
Carbon dioxide
Give three fates of sugar
It can be converted into starch or cellulose and can be used for respiration
Name three limiting factors of photosynthesis
Light intensity, carbon dioxide concentration and temperature
Define the term respiration
The process by which chemical energy is released during the breakdown of a food such as glucose
State the type of energy stored in ATP
Chemical energy
Describe how energy is released from ATP
When the final phosphate bond is broken to make ADP
Name the molecules produced following energy release
ADP + Pi
State four uses of energy in cells
Growth, repair, mitosis and muscle contraction
Describe how ATP is regenerated
When glucose is broken down during respiration, it releases energy that is used to regenerate ATP
State the word equation for aerobic respiration
Glucose + oxygen - carbon dioxide + water + energy
Name the molecule that is formed when glucose is broken down during respiration
Pyruvate
State where aerobic respiration occurs in the cell
Stage one (glycolysis) - cytoplasm Stage two - mitochondria
State the total number of ATP molecules produced when oxygen is available
38 ATP
Name the end products of aerobic respiration
Carbon dioxide and water
Give two examples of cells that require many mitochondria and why
Sperm cell - needs energy to swim to the egg
Muscle cell - makes up for all the muscles in the body
Name the type of respiration that occurs in the absence of oxygen
Fermentation
State the number of ATP molecules produced in the absence of oxygen
2 ATP
State the word equation for fermentation in animals
Glucose - pyruvate lactic acid
Name the molecule produced as a result of fermentation in animals
Lactic acid
State where fermentation occurs
Cytoplasm
State the word equation for fermentation in plants and yeast
Glucose - pyruvate - carbon dioxide + ethanol
Name the end products of fermentation in plants and yeast
Carbon dioxide and ethanol
Explain why fermentation is reversible in animals but irreversible in plants
In plants, gas is made which automatically diffuses out of the cell
