Topic 1: Cell Biology Flashcards
Practicals: Osmosis Diagrams: Animal Cell, Plant Cell, Prokaryotic Cell, Fluid Mosaic Model, Different phases of mitosis
Nucleus
Double membrane that stores DNA
Nucleolus
are in nucleus that makes ribosomes
Mitochondria
ATP production/aeorobic cell respiration + folded inner membrane increasing SA:V ratio
Golgi apparatus
Assembly of folded membranes for material secretion
Endoplasmic Reticulum
Network transports materials via vesicles
Smooth Endoplasmic Reticulum
Synthesises Lipids
Rough Endoplasmic Reticulum
Synthesises proteins
Vesicles
Membrane sacs involved in transport and storage of material
Peroxisomes
digestion of toxic metabolites
Lysosomes
breaking down cellular wastes
vacuoles
store excess fluids
ribosomes
protein synthesises on rough ER or cytosol
Chloroplasts
photosynthesis
Thylakoids
structure in chloroplasts where photosynthesis occurs
Exception; red blood cells
called erythrocytes, discard nucleus and mitochondria to increase SA:V ratio for more efficient gas exchange and ability to move through capillary vessels. eukaryote without a nucleus
Exception; Aseptate Fungal Hyphae
Tubular Projections of multicellular fungi that form a mycelium which have many nuclei
Exception; Skeletal Muscles
Large cells with many nuclei
Exception; Phloem Sieve Tube
Lose their nucleus and other organelles during development which allows space for transport
Nucleoid
Genetic Material in cytosol
Plasmids
DNA molecules exchanged to other prokaryotes
Pili
Hair-like extensions aid in adhesion/ plasma exchange
Flagella
Whip-like projections that aid in movement
Cell Theory
All living things are composed of cells, cells are the basic units of life, cells come form preexisting cells.
Endosymbiosis
Large cell taking in smaller cell by endocytosis. Mitochondria and chloroplasts - double membrane, susceptible to antibiotics, have their own DNA, divide similarity to binary fission, 70S ribosomes
Totipotent Stem Cells
Embryonic, can produce any tissue, only exist in early stages of life.
Pluripotent Stem Cells
embryonic, arise from totipotent, can produce all types of cells but not enough to make a whole organism
Multipotent Stem Cells
adult, only form some cells (bone marrow)
Unipotent Stem Cells
Adult, only forms sperm cells
Phospholipid
Part of the cell membrane. Hydrophobic and hydrophilic regions.
Phospholipid Bilayer
A phospholipid bilayer is one phospholipids spontaneously form into a bilayer; hydrophilic heads orientate towards the water and hydrophobic tails face away from the water.
What happens when the phospholipid bilayer is exposed to water?
Forms a micelle
What is a glycoprotein?
proteins with attached carbohydrate chains
What kind of molecule can diffuse quicker and easier across a cell membrane?
The smallest and less polar molecule. Therefore charged particles are unlikely to diffuse.
What does extracellular mean?
The outside side.
What does intracellular mean?
The inside side.
How are amino acids in a membrane localised?
According to polarity; non-polar, hydrophobic amino acids associate directly with the lipid bilayer but polar, hydrophilic amino acids are localised internally and face aqueous solutions.
What are integral proteins?
Helps transport substances that cannot diffuse across the membrane and they can also be receptors for hormones and neurotransmitters or enzymes for catalysing reactions.
What are peripheral proteins?
Hydrophilic so temporarily attached to the surface of integral proteins or connected to plasma membrane via hydrocarbon chain.
How do peripheral proteins behave on the extracellular side of a membrane?
Act as receptors for hormones/receptors or involved in cell recognition.
How do peripheral proteins behave on the intracellular side of a membrane?
Involved in cell signalling/chemical reactions and can also dissociate from the membrane and move into the cytosol.
What is glycosylation?
Phospholipid and membrane proteins that have carbohydrate chains that are attached via glycosylation.
What is a glycolipid?
Glycosylation of phospholipid
What is a glycoprotein?
Glycosylation of membrane protein
Freeze Fracturing
1966, Daniel Branton used freeze-fracturing to split cell membranes between two lipid layers -> Singer-Nicolson Model/Fluid Mosaic Model
What is passive transport?
Movement of material along a concentration gradient.
What is active transport?
Movement of materials against concentration gradient (low -> high)
What is simple diffusion?
Some substances can diffuse through membrane from a high conc. to a low conc. can only occur is there is a concentration gradient. Small uncharged particles pass between the lipid molecules. Directional movement is passive and continuous until molecules meet equilibrium.
What is facilitated diffusion?
Larger substances require carrier proteins to move between the membrane. carrier proteins carry proteins that are polar and larger; they are also integral glycoproteins which bind to a solute and undergo a conformational change to allow them to translocate the solute across the membrane but they have a slower rate of transport than channel proteins. Protein channels are integral lipoproteins which contains pore where ions can cross the membrane- ion-selective and may be gated to regulate the passage of ions in response to stimuli.
What is active transport?
Movement of substances across a membrane against the conc. grad. using energy from ATP - uses a special kind of carrier protein, protein pumps. Hydrolysis of ATP causes a conformational change in the protein pump. Allows cells to take up nutrients when their conc. outside the celll is low and allows cell to get rid of waster when the outside conc. is higher
What is osmosis?
Passive movement of water molecules from a region of low solute conc. to a region of high solute conc. across a partially permeable membrane. Cell membranes contain integral proteins called aquaporins that function as water channels to facilitate a faster rate of water transport.
Is water polar?
Yes it is but it is small enough to move between the phospholipid bilayer.
What does hypertonic mean?
Solutions with relatively higher solute conc. (high solute conc. gains water)
What does isotonic mean?
Equivalent solute conc. ( same solute conch. no net water flow)
What does hypotonic mean?
Solutions with relatively low solute conc. (low solute conc. looses water)
What is cell division?
Process of producing two cells from one, role is to ensure genetic info is passed onto next gen., parent cell produces the copy to make daughter cells
What is binary fission?
DNA replicate and cell separates into two cells
What are the two phases of the cell cycle?
Interphase and the M phase.
What is interphase?
Stage in the development of a cell between two successive division. Cell starts to inc. no. of organelles, cell will inc. in size and ,ass, plasma membrane and cytoplasm inc. in size, DNA is replicated, replicated DNA is arranged in a chromosome as 2 sister chromatids , 2 sister chromatids are attached at the centromere, further growth, proteins synthesised for division, DNA checked for errors by p53 proteins, microtubules form in preparation for mitosis.
What is the movement of chromosomes in the cell cycle?
Centrosome makes microtubule spindle fibres that guide chromosome to right place, motor proteins push/pull objects around cell and use microtubules as tracks, when cell is ready to separate chromosomes the motor proteins become active, the action of two microtubules sliding past each other pushes the two poles of centrosome away from each other
What are the four stages of mitosis?
Prophase, metaphase, anaphase, telophase.
What is prophase?
DNA is supercoiled into chromosomes by wrapping around histone proteins - chromatin -> supercoiling -> chromosome, nuclear envelope disintegrates and nuclei disappear, mitotic spindle forms as the centrosome builds new microtubules that will be used to pull chromosome into position, kinetochores (region in the centromere of each chromosome) attach to spindle, centrosome move towards opposite poles of cell as a result of lengthening microtubules.
What is metaphase?
Chromosomes move to the middle of cell, centromeres of the chromosome align on metaphase plate, chromosomes moves as a result of the action of the spindle.
What is anaphase?
Chromatids move towards opposite poles of cell, motor proteins push microtubules in opposing directions, centromeres move to poles first, at the end of this phase each pole has a complete identical set of chromosomes
What is telophase?
Set of chromosomes is at each pole, nuclear membrane (envelope) begins to re-form around each set of chromosomes, chromosomes start to elongate, nucleoli reappear, spindle apparatus disappears.
What is cytokinesis?
Once a cell reaches a certain size it splits into two, each cell receives a full copy of parent cell’s DNA and some essential organelles, cytoplasm is also split between the daughter cells.
What is oogenesis?
Only one egg develops during oogenesis to ensure the egg has ample nutrients
What is budding in yeast?
parent cell divides by producing small protrusion (bud) that grows into a new daughter cell.
