Cells as the Basis of Life Flashcards
Prokaryote
- Primitive
- Simple structured
- Unicellular
- Small with large surface area to volume ratios
- Do not have membrane-bound organelles
e.g. bacteria, photosynthetic bacteria (cyanobacteria), archaea (such as methanogens)
Eukaryote
- Complex cells
- Internal membrane-bound organelles
- Extremely diverse
- Uni or Multicellular
- Multicellularity and sexual reproduction are unique to eukaryotes
What are the four eukaryote kingdoms?
- Animalia
- Plantae
- Fungi
- Protista
First microscope inventors
Hans and Zacharias Janssen
Types of microscopes
Light microscope
Fluorescence microscopes
Electron microscopes
Confocal microscopy
Light microscope
Ones we use in school
Up to x1500
Living and non-living
Flourescent microscope
Used for flourescent material
- Stains
- Dyes
- Antibodies
Visualise smaller structures
Target proteins, detect disease
Confocal microscopy
Produces 3D views/models of structures
Very expensive
Obtains optical sections of cells stained with flourescent markers
High-res views of small structures
Electron microscope
Uses an electron beam rather than light
Higher res with greater depth of field
Produces black and white
More detail
Organelles
Membrane-bound internal structures with specific functions
Found in all eukaryotes
Types of Organelles
Nucleus
Ribosomes
Endoplasmic Reticulum (smooth + rough)
Golgi Apparatus
Lysosomes
Mitochondria
Chloroplast
Vacuole
Cell Wall
Cell Membrane
Nucleus
Contains most of the genetic material
Control centre of the cell, coordinates cell activities
Ribosomes
Only seen using electron microscope
Sites of protein synthesis
Translate the sequence of amino acids specified by mRNA into proteins
Non membrane-bound organelle
E.R.
Rough or smooth
Rough has ribosomes attached
produce and export of proteins
Smooth has no ribosomes attached
contains enzymes involved in synthesis of proteins, phospholipids and steroids
Golgi Apparatus
Golgi body/complex
Stack of flattened membrane sacs (cisternae)
Transport proteins for modification for use
Lysosomes
Recycling units
Digest unwanted matter
Enzymes help digest matter, and is either reused and diffused into cytoplasm, retained in the lysosome or released from the cell
Mitochondria
Powerhouse of the cell
Inner and outer membrane
Cellular respiration site
Converts chemical energy to energy cells can use
Chloroplast
Involved in photosynthesis
Contains chlorophyll
Inner membrane, outer membrane and thylakoid system
Only seen in plant cells
Vacuole
Stores enzymes and other organic and inorganic molecules
Singular and big in plant cells
Many small, temporary in animal cells
Provide structural support by helping maintain turgot in plants
Similar to lysosome in animal cells
Cell Wall
Surrounds cell membrane of plant cells, fungal cells and some prokaryotes
Mostly cellulose, chitin in fungal cells
Provides support, prevents expansion, allows water + dissolved substances to pass through
Lignin in cells of woody plants, especially xylem, gives more strength
Cell Membrane
Controls exchange of material between internal and external environments
Selectively permeable
Cannot be seen using microscopes
Encloses cell contents
Cell recognition and communication
Seen using fluid mosaic model
Fluid Mosaic Model
Shows cell membrane
Presents bilayer of phospholipids
Other molecules are scattered throughout bilayer
Hydrophilic head and two hydrophobic tails
Transport proteins - passageways allowing substance to move across membrane
Receptor proteins - responce to certain signals (hormones)
Glysoproteins - identify the cell, called antigens or marker molecules
Diffusion
Passive transport
movement of any molecules from high concentration to low concentration until equilibrium
Concentration gradient
Osmosis
Diffusion of water molecules across semipermeable membrane
Osmotic gradient, osomotic pressure
Active transport
Hypotonic
Solution contains lower concentration than the cell
Movement will be into cells
Hypertonic
Solution contains higher concentration than the cell
Movement will be out of cells
Isotonic
Equal concentration of solution and cell
Movement will be equal in both directions
Active Transport
Requires energy
Generally against a concentration gradient
Passive Transport
Doesn’t require energy
Generally with a concentration gradient
Facilitated Diffusion
Required for large molecules and charged particles
Require carrier proteins and channel proteins
Endocytosis
The process which large particles are moved into the cell using help of the cell membrane
Phagocytosis
Particle engulfed by membrane and material is digested
Pinocytosis
Membrane engulfs liquid containing dissolved molecules
Receptor-Mediated Endocytosis
Pinocytosis that is initiated by protein receptors on cell membrane
Exocytosis
The process which substances, such as antibodies, neurotransmitters and enzymes that have important functions elsewhere and waste products in the organ need to be removed
Removal of substance
Permeability
Ability to allow the cell to exchange liquids and materials between the cell’s internal and external environment
Critical to it’s function and survival
Selective (semipermeability)
Factors affecting Diffusion
Size of molecule - glucose and amino acids are large, requiring facilitated diffusion
Concentration gradient - relative concentration of solutes affect the speed at which diffusion occurs
Surface area to volume ratio (SA:V) - smaller the cell, larger the SA:V, substances reach centre of cell faster than one with a small SA:V
Cellular Respiration
Photosynthesis for photoautotrophs
Break down of glucose as a source of energy to drive cellular respiration
Aerobic or anaerobic respiration
Alcohol Fermentation
Many bacteria carry out anaerobic respiration
Breaks down glucose to form ethanol and carbon diocide, producing ATP
Lactic Acid Fermentation / Formation
When an organism can’t produce enough energy through aerobic respiration
During strenuous/continued exercise when not enough energy is delivered to muscles
One molecule of glucose is broken down in the absebce of oxygen, produces two molecules of lactic acid, and two ATP
Aerobic Respiration
Oxygen present
Glucose + Oxygen -> Carbon Dioxide + Water + ATP
Enzymes
Protein molecules
Controls metabolic reactions in living cells
Catalysts, control rate of chemical reaction occurring in cells
Composed of protein molecules
Active site where reactants (substrates) in a chemical bind to
Enzyme Models
Lock and Key
Induced Fit
Factors affecting Enzyme Activity
Temperature - too hot, changes the shape of the active site, denatures the enzyme, too cold, function slows down or stops
pH - outside the range denatures the enzyme, altering shape of the active site
Substrate concentration - speed of activity, more substrate, takes longer to react as there are less available enzymes
Enzyme concentration
Organic molecules
Carbon attached to hydrogen in molecule
carbs, lipids, proteins, nucleic acids
Inorganic molecules
Carbon (if present) not attached to hydrogen
water, oxygen, carbon dioxide, nitrogen, minerals
Autotrophs
Create their own food (e.g. photosynthesis)
Heterotrophs
Consume other organisms for food
Photosynthesis
Process in which plants utilise light energy, trap it in chlorophyll inside chloroplast and create glucose for fuel
Carbon Dioxide + Water -(light energy and chlorophyll)-> Glucose + Oxygen
Light-Dependent Stage of Photosynthesis
Chlorophyll captures solar energy, uses it to produce ATP (adenosine triphosphate)
Photolysis occurs, water is split to hydrogen ions and oxygen gas
Water -(Light Energy + Chlorophyll)-> Hydrogen Ions + Oxygen + ATP
Light-Independent Stage of Photosynthesis
“Dark Reactions”
Produce glucose, water, ADP (adenosine diphosphate)
Hydrogen Ions + ATP + Carbon Dioxide -> Glucose + Water + ADP
Uses energy from stage 1 to form glucose
