Sem 2 - AOS 1 Flashcards
What are the 3 parts of Cell Theory?
- All organisms are composed of cells.
- The cell is the basic unit of structure and organisation in organisms.
- All cells come from pre-existing cells.
What does every cell have?
- Plasma Membrane
- Cytosol
- DNA
- Ribosomes
Prokaryotic Cells;
- No membrane bound organelles
- No nucleus
- Single Celled Organisms - Bacteria + Archaea
Eukaryotic Cells;
- Contain membrane bound organelles
- Have a nucleus
- DNA is located in the nucleus
- Animals, Plants, Fungi and Protists
Cells Changing Shape
Not all cells have a fixed shape;
- Cells with a cell wall can’t change shape
Surface Area to Volume Ratio
The higher the SA:V ratio, the greater efficiency of two-way exchange of materials across the plasma membrane.
Plasma Membrane
Function: boundary of a cell; maintains the internal environment of a cell by controlling the movement of substances into and out of the cell.
Found in both Prokaryotes and Eukaryotes.
Contains both lipid and protein
Have a phospholipid bilayer
Plasma membrane is said to be semipermeable or selectively permeable.
Cell Wall
Are only found in plant, fungi and bacterial cells.
• Are semi-rigid and are a protective barrier.
• Are located outside of the cell membrane.
• The composition of the cell wall varies in each type of organism:
Plants = cellulose (fiber)
Fungi = Chitin (Carbohydrate).
Bacteria = Complex polysaccharides
Nucleus
Control center of the cell.
• Contains all genetic information – DNA (Deoxyribonucleic Acid).
• Is surrounded by a double membrane known as the nuclear envelope.
• Most Eukaryotic cells have one nucleus (exceptions –
Some Liver cells have two. Red blood cells have none
except, when they are first made)
Mitochondria
Known as the “Powerhouse of the cell.” • Cellular respiration occurs in the mitochondria to release energy for the cell to use. • Is bound by a double membrane. • Has its own strand of DNA. • ATP: Adenosine triphosphate
Cytoplasm and Cytosol
Is a clear fluid within cell that contains all organelles excluding the nucleus.
• It moves materials throughout the cell.
• The cytosol is the fluid contents only of a eukaryotic cell.
Ribosomes
Is the site of protein synthesis.
• Are composed of protein and RNA.
• Are not enclosed in the membrane but found attached to rough ER or floating free in cytoplasm.
Endoplasmic Reticulum
Endoplasmic Reticulum (ER) is a series of membranous channels used for transport within cells.
• Rough ER is studded with ribosomes and makes proteins.
• Smooth ER: has no ribosomes and makes lipids.
• Is series of folded membranes.
Golgi Complex
- Stores, modifies and packages proteins for transport.
- Shifts proteins out of cells.
- Molecules are transported to and from the Golgi by means of vesicles.
- Cells that make saliva or mucus have many Golgi bodies.
Lysosomes
- Is the principal site of digestion within a cell
- Contain digestive enzymes that break down wastes.
- Are found in Golgi bodies.
- Help white blood cells to destroy bacteria.
- Apoptosis is programmed cell death.
Peroxisomes
Found in both plant and animal cells
Breakdown of substances that are toxic
Chloroplasts
- Are the site of Photosynthesis and Starch storage.
- Are only found in plant and algae cells.
- Contains the green pigment chlorophyll.
- Are bound by a double membrane
- Not present in all plant cells
Flagella and Cilia
Are found in protists and animals, and are very rare in plants)
For unicellular organisms they aid in movement.
Cilia are shorter than flagella and multiple cilia can occur on a cell.
Cilia can be found in the trachea.
Sperm have a flagella
Cytoskeleton
Acts as skeleton and muscle and provides shape and structure to the cell. • Helps move organelles around the cell. • Is made of three types of filaments • Microtubules • Actin filaments • Intermediate filaments
Vacuole
- Plants have a Large central vacuole
- Animals have smaller vacuoles
- Are the storage container for water, food, enzymes, wastes, pigments, etc.
- Help plants maintain their shape.
Plasma Membrane Structure - Phospholipids
The main structural component of the plasma membrane.
Double layer (bilayer) of phospholipids.
Consists of two fatty acid chains joined to a
phosphate-containing group.
The phosphate-containing group = hydrophilic head.
The fatty acid = hydrophobic tail
Plasma Membrane Structure - Proteins
Integral proteins are embedded in the phospholipid
bilayer.
Trans-membrane proteins span the width of the plasma
membrane with part of the protein being exposed on both sides of the membrane.
Glycoprotein are carbohydrate groups that attach
themselves to proteins.
Peripheral proteins are either anchored to the exterior
of the plasma membrane or are indirectly associated with the plasma membrane
Ways of crossing Plasma Membrane
- Simple diffusion is the means of transport of small lipophilic substances. Water can also move across the plasma membrane by diffusion; this is a special case of diffusion known as osmosis.
- Facilitated diffusion involves protein transporters and is the means of transport of dissolved hydrophilic substances down their concentration gradients.
- Active transport involves protein transporters known as pumps and is the means of transport of dissolved hydrophilic substances against their concentration gradients.
- Endocytosis/exocytosis are the means of bulk transport of macromolecules and liquids.
What is Diffusion?
Diffusion is the net movement of a substance, typically in solution, from a region of high concentration of the substance to a region of low concentration across a semi-permeable membrane until equilibrium is met
Osmosis
The net movement of water molecules from a solution of high water concentration to one of lower concentration across a semipermeable membrane until equilibrium is met
Osmosis types
- hypotonic — having a lower solute concentration than the cell contents
- isotonic — having an equal solute concentration to that of the cells
- hypertonic — having a higher solute concentration than the cell contents.
Facilitated Diffusion
Protein-mediated transport.
does not require an input of energy.
Dissolved substances requires the action of protein
transporters that are embedded in the cell membrane.
Active Transport
Moves dissolved substances from a region of low
concentration to a region of high concentration of those
substances.
Requires an input of energy (ATP).
Pumps are proteins with both a transport function and
an enzyme function. The enzyme part of the pump
catalyses an energy-releasing reaction:
ATP → ADP + Pi + energy
Bulk Transport
Involves transporting solid particles into and out of a cell.
Endocytosis = into a cell.
Phagocytosis = solid food particle
Pinocytosis = solution
Exocytosis = transport out of the cells.
What does cellular respiration do?
ATP is formed when energy is released during cellular respiration of glucose.
Aerobic Cellular Respiration
Aerobic respiration uses oxygen
Glucose + Oxygen Carbon dioxide + Water + 30/32ATP
Anaerobic Cellular Respiration (Fermentation)
doesn’t use oxygen
Humans: Glucose Lactic Acid + 2ATP
Yeast: Glucose Alcohol + Carbon dioxide + 2ATP
Cellular Respiration - Aerobic Respiration Process
Step 1: Glycolysis in the cytosol glucose molecules are broken down into two molecules of pyruvate.
Step 2. Kreb’s Cycle in the matrix of the mitochondria. Pyruvate is broken down into carbon dioxide
Step 3. Electron Transport Chain in the inner membrane (cristae) of the mitochondria where oxygen combines with hydrogen ions to form water
Cellular Respiration - Anaerobic Respiration Process
Occurs in cytosol
Doesn’t require oxygen
Humans: Glucose Lactic Acid + 2ATP
Yeast: Glucose Alcohol + Carbon dioxide + 2ATP
What does Photosynthesis do?
Photosynthesis is the process in which light energy is transformed into chemical energy stored in sugars.
Occurs in Chloroplasts
Photosynthesis Equation
Carbon Dioxide + Water Glucose + Oxygen
or
6CO2 + H20 = 6CH12O6 + 6O2
Photosynthesis - Light Dependent Stage
Occurs with the grana (the thylakoid membranes) of
chloroplasts.
Uses light energy to split water into oxygen and hydrogen ions
Photosynthesis - Light Independent Stage
Occurs in the stroma (cytoplasm of chloroplast)
Carbon dioxide combines with the hydrogen ions to form glucose
