Cells And Microscopy Flashcards
State the two types of cells.
-Eukaryotic (animals and plants
-Prokaryotic
What is the difference between a Eukaryotic and Prokaryotic cell?
Eukaryotic - contains a nucleus and membrane-bound organelles
Prokaryotic- doesn’t
List 5 components of both plant and animal cells
-Nucleus
-Cytoplasm
-Cell membrane
-Mitochondria
-Ribosomes
How is genetic information stored in a Eukaryotic cell?
Within the nucleus, arranged in chromosomes
Other than storing genetic information, what is the function of the nucleus?
Controls cellular activities
Describe the structure of the cytoplasm.
Contains organelles, enzymes and dissolved ions and nutrients
What’s the function of cytoplasm?
Site of cellular reactions e.g first stage of respiration
What’s the function of the cell membrane?
Controls the entry and exit of materials into and out of the cell
What’s the function of mitochondria?
Later stages of aerobic respiration in which ATP is produced
What’s the function of ribosomes?
Joins amino acids in a specific order during translation
What 3 organelles are found in plant cells only?
-Large, permanent vacuole
-Cell wall
-Chloroplasts
What’s the cell wall made of?
Cellulose
What’s the function of the cell wall?
-provides strength
-prevents the cell bursting when water enters by osmosis
What does the permanent vacuole contain?
A solution of salts, sugars and organic acids
What’s the function of the permanent vacuole?
Supports the cell, maintaining its turgidity
What’s the function of chloroplasts?
Site of photosynthesis
What are the 6 organelles found in Prokaryotic cells?
-Chromosomal DNA
-Plasmid DNA
-Cell wall
-Cell membrane
-Ribosomes
-Flagella
What are plasmids?
-small, circular loops of DNA found free in the cytoplasm and separate from the main DNA
-carry genes that provide genetic advantages
What’s flagellum?
Enables bacteria to move
What is a haploid cell?
Cell that contains a single copy of each chromosome (half the number of chromosomes)
E.g 23 chromosomes in humans
What’s a diploid cell?
Cell that contains two copies of each chromosome
E.g 46 chromosomes in humans
What are gamates?
-Reproductive cells (egg and sperm cells)
-They are haploid cells
How are egg cells adapted to their function?
-haploid nucleus contains genetic material
-mitochondria in cytoplasm produce energy for the developing embryo
-cytoplasm contains nutrients
-cell membrane hardens after fertilisation
How are sperm cells adapted to their function?
-haploid nucleus contains genetic information
-tail enables movement
-mitochondria provides energy for tail movement
-acrosomes contains enzymes that digest the egg cell membrane
How can the magnification of an image be calculated?
Magnification = size of image/ size of specimen
How do light microscopes work?
Passes a beam of light through which travels through the eyepiece lens
What are 4 advantages of light microscopes?
-inexpensive
-easy to use
-portable
-observe both living and dead specimens
What is a disadvantages of light microscopes?
Limited resolution
How does an electron microscope work?
Uses a beam of electrons which are focused using magnets, electrons hit a fluorescent screen which emits visible light, producing an image
What’s an advantage of an electron microscope?
Greater magnification and resolution
What are 4 disadvantages of an electron microscope?
-expensive
-large so less portable
-require training to use
-only dead specimens can be observed
What are enzymes?
Biological catalysts that increase the rate of a chemical reaction without being permanently altered themselves
What’s an advantage of enzymes in the body?
They enable cellular reactions to take place at lower temperatures
What is the active site of an enzyme?
Substrate molecule binds and the reaction takes place
Why are enzymes described as having a ‘high specificity’ for their substrate?
Only substrates with a specific, complementary shape can fit into an enzymes active site
Describe the ‘lock and key’ model?
-substrate collides with the active site of an enzyme
-substrate binds, enzyme-substrate complex forms
-substrate converted to products
-products released from the active site which is now free to bind to another substrate
What factors affect the rate of an enzyme-controlled reaction?
-temperature
-pH
-substrate concentration
Explain how increasing temperature initially affects the rate of an enzyme-controlled reaction.
-as temp increases molecules have more KE
-movement of molecules increases
-probablility of a successful collision increases
-more enzyme-substrate complexes form
-rate of reaction increases
Explain how increasing temperature above the optimum affects the rate of an enzyme-controlled reaction.
-temp increases above optimum
-increased vibrations break bonds in enzymes structure
-active site changes shape, enzyme is denatured
-no enzyme-substrate complexes can form
-rate of reaction decreases
How can the rate of an enzyme-controlled reaction be calculated when given a value for time?
Rate= 1/ time
What are the units for rate?
S^-1
Why must large organic molecules be broken down into smaller, simple molecules in the body?
-large molecules are too big to be absorbed across the surface of the gut wall
-large molecules are broken down into smaller molecules for absorption into the bloodstream
Give an example of the breakdown of large molecules into smaller molecules in plants.
Starch is broken down by enzymes into simple sugars which are respired to release energy
What type of molecules are proteins are carbohydrates?
Polymers
What are the monomers of carbohydrates?
Simple sugars
Which group of enzymes catalyses the breakdown of carbohydrates?
Carbohydrases
Which type of carbohydrase catalyses the breakdown of starch?
Amylase
What are the monomers of proteins?
Amino acids
Which type of enzyme catalyses the breakdown of proteinss.
Proteases
What is the function of lipases?
Enzymes which catalyse the breakdown of lipids into fatty acids and glycerol
Which enzyme catalyses the formation of glycogen from glucose?
Glycogen synthase
What is simple diffusion?
The net movement of molecules from an area of high concentration to an area of low concentration
What molecules enter and leave cells via simple diffusion through the cell membrane?
Small molecules e.g oxygen, water, glucose, amino acids
What 3 factors affect the rate of diffusion?
-temperature
-concentration gradient
-surface area of cell membrane
Define osmosis.
The net movement of water molecules from an area of high water concentration to an area of low water concentration through a partially permeable membrane
What is active transport?
The movement of molecules across a cell membrane from an area of low concentration to an area of high concentration
How is percentage change in mass calculated?
% change = final mass-initial mass/ initial mass x 100
What’s the role of the nucleus?
Controls cells activities
