IB Biology: Cells

34 flashcards · Other · by Gabrielle Wong

The principles of cell theory are: Cells are the smallest units of life All living things are made of cells All cells come from existing cells
Exceptions to cell theory: Muscle Cells and Fungal Hyphae: multi-nucleated, continuous cytoplasm, chitin-cell wall Viruses: don't exhibit all signs of life Amoebae: single celled organisms capable of all life processes Where did the first cells come from?
The functions of life are: Growth: ability to change Excretion: ability to remove waste Metabolism: chemical reactions within cell Response to stimulus: able to respond to what is occuring in environment Reproduction: able to produce offspring Homeostasis: retention of the same envrionment within a certain range of values through the use of negative feedback loops Nutrition: ingestion of molecules for use by the cell Movement: ability to move
Movement is not always considered a function of life.
The three types of cells are...
Prokaryotic, animal, plant
SA: V Ratio Heat, waste, and consumption depend on volume Volume grows faster per unit than SA Certain ratio is necessary for efficiency
Large cells have a lower ratio, and if they are too large, they will be non-functional, which limits cell size. Work-arounds: Long and thin cells Inner folds
Emergent properties: arise from the interaction of component parts: the whole is greater than the sum of the parts
Emergent properties explain why cells are able to function together to create complex organisms like the human body even though their ultrastructures are the same.
Differentiation: means that some genes are expressed but not others
Stem cells are importnat in the process of differentiation, as they are still capable of doing it, unlike some other cells (ex. nerve cells). Differentiation leads to specialization of cells.
Stem cells: cells that retain the capacity to divide and have the ability to differentiate along different pathways. They can be harvested from embryos (ethical issues), umbillical cord blood (also ethical issues), or adults.
There are different types of stem cells: Pluripotent: any kind of cell but embryonic membrane Multipotent: several types of body cells Nullipotent: incapable of division
Stem cells can be used for therapeutic purposes.
Examples Using stem cells and injecting them into bone marrow to treat leukemia Possibility of using stem cells to treat Stargardt's disease (condition caused by inability to process Vitamin A properly, leading to degeneration of photoreceptor cells, leading to eventual blindness)
Who conducted an experiment that explained why cells did not spontaneously generate?
Pasteur
The Endosymbiotic Theory: A prokaryote ate another prokaryote The cells formed a symbiotic relationship (the engulfed cell received protection and food, the other cell got energy) Over time, evolution to eukaryotes
Evidence for this: presence of mitochondria and choloroplasts presence of DNA, 70s ribosomes, the division of these organelles via binary fission, and their size
Prokaryotic cells Capsule Flagella Pili Glycolayx Cell membrane Cytoplasm Nucleoid region Ribosomes (70s) Plasmid Inclusion body
structure, shape movement attachment, DNA transfer protection, moisture, attachment regulation of materials chemical reactions of cell single naked DNA thread, control of cell, reproduction protein synthesis abormal circumstances, DNA transfer storage
Animal cells Cell membrane nuclear pore nucleus nucleolus rough ER Ribosomes (80s) Smooth ER Golgi body mitochondria Vacuole Lysosome Ctyoplasm Centrioles
regulation of materials regulation of materials storage of DNA ribosome and mRNA produciton protein synthesis protein synthesis function depends on cell type stores, packs, transports proteins cellular respiration stoarge digestion of old cell parts location of chemical reacitons mitosis
Plant cells Cell wall Cytoplasm Cell membrane Vacuole Nuclear pore Nucleolus Nucleus Chloroplast Mitochondria Rough ER Ribosomes (80s) Golgi Body Smooth ER
support, stucture,, protection location of chemical reactions regulation of materials storage regulation of materials ribosome and mRNA production storage of DNA photosynthesis cellular respiration protein synthesis protein synthesis stores, packs, transports proteins function depends on cell type
Comparions of prokaryotes and eukaryotes Prokaryotes store DNA openly, whereas eurkaryotes use the nucleus In prokaryotes, DNA is a naked loop, whereas eurkaryotic DNA is associated with histone proteins Only eukaryotes have mitochondria Both have ribosomes; they are 70s in prokaryotes and 80s in eukaryotes. Only eurkaryotes have compartmentalized, meaning they have different organelles. Prokaryotes usualy have pili, plasmids, and a flagella; eukaryotes usually lack all of hese Prokaryotes and…
For compare questions, differences and similarities are needed.
Comparisons of plant and animal cells Both have cell membranes, but only plant cells have a cell wall Animal cells have cholesterol in their membranes; plants don't Only plant cells have chloroplasts, which are for photosynthesis In plant cells, vacuoles are far larger Glucose is stored as starch in plants and glycogen in animals Animal cells have centrioles; plants do not. The shape of each is different; plants are more angular; animals are more flexible. Both have mitochondria for cellular re…
For compare questions, differences and similarities are needed.
Phospholipids A lipid molecule where one of the fatty acid chains is replaced by a phosphate group leaving a hydrophillic phosphate group and two hydrophobic fatty acid chains attached to the glycerol
Phospholipids form a bilayer - fluid-mosaic model of the cell membrane (this is because of their hydrophillic/hydrophobic nature)
Integral protein: protein that goes completely through the bilayer
Part of the fluid-mosaic model
Peripheral protein: protein found on the surface of the bilayer
Part of the fluid-mosaic model
Phospholipid bilayer: main component of model, formed with hydrophillic heads and hydrophobic tails
Part of the fluid-mosaic model
Glycoprotein: protein with a carbohydrate chain attached to it
Part of the fluid-mosaic model
Cholestoerol: found only in animal cells, helps to regulate fluidity of membrane
Part of the fluid-mosaic model
The functions of membrane proteins are hormone binding sites catalyzing of enzyme reactions electron carriers - often chains passive channels ex. for faciliated diffusion active channels - those that require ATP communication - carb molecules serve as identification cell adhesion - formation of hooks and tight junctions
These are all relevant in other parts of the course as well - be sure to make the connections ex. Na-K pump, role in action potentials
Passive transport: transport occuring along a concentration gradient, does not require ATP
Types of passive transport: Diffusion Faciliated diffusion Osmosis
Active transport: transport occurring against a concentration gradient, requires ATP
Types of active transport: Exocytosis Endocytosis Na-K Pump
Diffusion: movement of a high concentration of a substance to lower concentrations until equilibrium is reached
Whether or not diffusion occurs depends on size and polarity of the molecule ex. diffusion of O2 and CO2
Faciliated diffusion: requries a carrier protein, the protein changes shape to allow materials through
Even though shape change occurs, facilitated diffusion does not use ATP.
Osmosis: the passive movement of water across a semi-permeable membrane from areas of lower solute concentration to higher solute concentration.
How water moves depends on the type of solution Hypertonic = solution has higher concentration, water moves into this solution Hypotonic = solution has lower concentration, water moves out Isotonic = concetrations are equal, net movement of water is zero
Sodium-Potassium pump: sodium moves out, potassium moves in
Process: protein binds to 3 sodium ions phosphorylation turns ATP to ADP protein changes shape, release of Na potassium ion binds, release of phosphates Shape change again, allowing potassium in
Endocytosis: the process through which a material moves into a cell
Process: Particle is enclosed by a vesicle Membrane fluidity allows it to sink and enclose seals back to form the vesicle vesicle breaks away from cytoplasm into the cell ex.. phagocytosis - ingestion of "not-self" particles by macrophage white blood cells
Exocytosis: the process through which a material moves out of a cell
Process: vesicle transports to cell membrane vesicle fuses with the flexible bilatyer fusion leads to phospholipids joining togeter and becoming part of the membane material is secreted ex. release of hormones
Mitosis: The stages are: prophase, metaphase, anaphase, telophase Prophase: coiling to form chromosomes (condensing), nuclear envelolope and nucleoulus disappear, formation of the spindle, centrosomes move to opposite ends, leading to the lengthening of the spindle micotubules Metaphase: chromosomes move to equator and line up on the plate (due to the movement/tugging of the spindle microtubules) Anaphase: spindle contracts, centromere is pulled apart, the sister chromatids are split apart and…
Mitosis leads to the production of two genetically identical daugher cells, and is immediately followed by cytokinesis.
Cyclins: proteins that create checkpoints at each stage of the cell cycle to ensure proper function
Stages of the cell cycle: Interphase: growth, DNA replcation, more growth and prep for mitosis Mitosis Cytokinesis
Cytokinesis: the splitting of the cell into two
Within animals: formation of a cleavage furrow (contractile ring of microfilaments) Within plants: vesicles from a cell plate that create a cell wall that eventually splits
Cancer: caued by out-of-control reproduction Turmor: mass of abnormal cells
Primary tumors are the original tumor Metastatic tumors are secondary, caused by spread Cancer can be caused by mutagens (ex. cigar smoke), which trigger oncogenes, mutate genes that could cause cancer when expressed frequently