Cells - Key Words Flashcards
Parts of a prokaryotic cell
Parts of a prokaryotic cell: Cell wall, capsule, cell membrane, flagellum, circular DNA, plasmid, ribosomes, cytoplasm, circular DNA.
Nucleus
Nucleus – (incl. nuclear envelope, nuclear pores, nucleoplasm, chromatin, nucleolus) Storage site of genetic information, the site of DNA replication and its transcription to RNA (mRNA and tRNA). Manufacture ribosomal RNA and ribosomes.
Plasmid
Plasmid - Small circles of DNA, used to exchange DNA between bacterial cells.
Circular DNA
Circular DNA - contains genetic information to let cells replicate. Not associated with proteins.
Mitochondria
Mitochondria are in cells because:
- Mitochondria release energy/ produce ATP
- From aerobic respiration
- Double membrane – controls entry and exit of material
- Contain cristae (shelf like extensions of inner membrane – large SA for enzymes in respiration to attach to) & matrix (contains enzymes for respiration)
Cell wall
Cell wall - Made of peptidoglycan (Murein). Protects cell against damage
Cytoplasm
Cytoplasm – contains enzymes for metabolic reactions
Capsule
Capsule - Thick polysaccharide layer outside of the cell for protection/helps groups of bacteria stick together for more protection
Ribosomes
Ribsosomes – 80S type in eukaryotic cells (bigger)/70S in prokaryotic.
-Make proteins (remember enzymes are proteins)
Flagellum
Flagellum – tail for movement. Helps spin cell through fluids
Rough endoplasmic reticulum
Rough ER (RER) - Surface ribosomes bind to for protein synthesis. Provides pathway for transport of materials around the cell.
Smooth endoplasmic reticulum
Smooth ER (SER) - Makes, stores and transports lipids and carbohydrates
Comparing prokaryotic and eukaryotic cells
-Bacteria don’t have a nucleus/nuclear membrane, eukaryote does;
-Bacteria don’t have membrane-bound organelles, eukaryote does;
-Bacteria don’t have mitochondria, eukaryote does;
-Bacteria has 70S/smaller ribosomes, eukaryote has 80S/larger;
Bacteria cell- have murein/peptidoglycan cell wall, eukaryotes do not-.
Bacterial cells - smaller than eukaryotic cells;
Bacteria - circular DNA, eukaryotes - linear DNA;
Bacteria may have capsules, eukaryotes don’t;
Golgi body
Golgi Body - Modifies polypeptide chains into mature proteins. Sorts and ships lipids for secretion or use within the cell. Makes secretory enzymes. Forms glycoproteins. Modified proteins and lipids are transported in golgi vesicles.
Centrifugation
Centrifugation – helps to separate organelles. Most dense organelles separate 1st, forming a pellet, which is removed. Supernatant contains other organelles –can spin again
Lysosomes
Lysosomes - Break down and recycle materials in the cell.
Contain proteases, lipases and lysozymes
Centrifugation types
Centrifugation;
Cold – slows down / stops enzyme activity to prevent digestion of organelles
Isotonic – prevents osmosis –so no lysis/ bursting/shrinking of organelles
Buffer - prevents damage to enzymes / proteins (denaturing); Maintains pH
Homogenised to à break open cells and release content. Filtered to remove unbroken cells / larger cell debris.
Steps in centrifugation
Steps in centrifugation
• Chop up cells
• Homogenise
• In a cold, isotonic buffer solution
• Filter and centrifuge filtrate
• Organelle making up most of the pellet after being spun at a low speed = nucleus.
• (If continuing) – Centrifuge supernatant at a higher speed – Mitochondria might come next (refer to question here)
Adaptions of epithelial cells for absorption
Adaptations of epithelial cells for absorption
-Microvilli- large SA
-Many mitochondria; - release energy- active transport
-Carrier proteins for active transport & fac diffusion
-Co-transport of sodium (ions) and glucose
-Membrane-bound enzymes digest disaccharides / produce glucose
(left in because it does come up later in absorption)
Cell wall (in plants, algae and fungi)
Cell wall (in plants, algae and fungi)
Plants: Consists of microfibrils of cellulose
-Middle Lamella – thin layer that marks the boundary between adjacent cell walls and cements them together.
Functions: Mechanical strength, pathway for water transport in the plant.
Algae: Cellulose or glycoproteins or a mixture of both.
Fungi: Do not contain cellulose but Chitin, glycan and glycoproteins.
Cell vacuole in plants
Cell Vacuole (in plants)
A fluid filled sac bounded by a single membrane – tonoplast.
Contains salts, sugars, a/a, wastes ad pigments
Functions: Support – turgid, temporary food store, pigments may colour petals – attract insects
Magnification
Magnification = Image/Object
Being able to enlarge something in appearance.
Light and electron microscopes
Light (optical) and electron microscopes. 2 types of electron microscopes – TEM and SEM
- TEM – Black/white image
- SEM -3D image
Benefits of electron microscopes
Benefits of electron microscopes (vs light)
- Have a higher resolution (than light microscopes) because the electron beam has a shorter wavelength
- Thus can see smaller objects – has a higher resolving power
Eye piece graticule
Eye piece graticule - is a glass disc fitted into the eyepiece of the microscope. The absolute size of the scale is not important as this is what will be calibrated.
Stage micrometer
Stage micrometer - is used to calibrate the eyepiece graticule. A stage micrometer consists of a microscope slide on which is engraved a fine and accurate scale. We use this to calibrate the eyepiece graticule.
Using an eye piece graticule
Using an eye piece graticule
- Measure (each stoma) using eyepiece graticule;
- Calibrate eyepiece graticule against stage micrometer / ruler / graph paper;
- Take a number of measurements (to calculate a mean)
Benefits of light microscopes
Benefits of light microscopes (vs electron)
- Can look at living cells- don’t have to be in vacuum
- Can produce colour images
Artefacts
Artefacts - things that result from the way the specimen is prepared. They are not part of the natural specimen.
Parts of a eukaryotic cell
Parts of a eukaryotic cell: Cell surface membrane, Nucleus (including chromosomes, consisting of protein bound linear DNA and one or more nucleoli), mitochondria, Chloroplasts (in plants and algae) rough endoplasmic reticulum (RER), smooth endoplasmic reticulum (SER), ribosomes, golgi body and golgi vesicles, lysosomes, cytoplasm, cell wall (in plants, algae and fungi), cell vacolue (in plants), starch grains (plants).
