cell division Flashcards
Cell Membrane
Soft and flexible
Separates inner and external environments
Controls the flows of materials in and out of the cell
Centrioles
ONLY FOUND IN ANIMAL CELL
Controls movement of chromosomes during cell division
Cytoplasm
A jelly like substance full of proteins and nutrients that fill the cell
The other organelles are suspended in the cytoplasm
Cytoskeleton
Strand of proteins that gives the cell its shape and helps it move.
Acts as tracks on which vacuoles and organelles move.
Endoplasmic Reticulum
Transports materials made in cells
Rough E.R: covered in ribosomes and associated with making proteins.
Smooth E.R: associated with production of fats and oils and does not have ribosomes on it.
Golgi Apparatus
Modifies, sorts and packages proteins for transport within or out of the cell
Lyosomes
ONLY FOUND IN ANIMAL CELLS
Contains enzymes to digest invading bacteria or damaged organelles
Mitochondria
Make energy from nutrients
Make all energy for the cells
Mitochondrion = Singular
Mitochondria = Plural
Nucleus
Contains the cell’s DNA
Controls cell activity : growth & reproduction
Contains the Nucleolus which makes ribosomes.
Ribosomes
Make proteins
Found in the cytoplasm and on the Rough E.R
Vacuoles
Holds water and other materials
Used to move small molecules around the cell
Plants cells have one big Vacuole
Animals cells have small many Vacuole
Vesicles
Used to move materials into and out of the cell
Cell Wall
ONLY FOUND IN PLANTS
A hard wall outside of the cell membrane
Protects the cell and gives it shape and strength
Chloroplasts
ONLY FOUND IN PLANT CELLS
Where photosynthesis happens (Makes sugar from CO2, H2O and Sunlight)
Which are only found in Animal Cells?
Lyosomes
Centrioles
Which are only found in Plant Cells?
Cell Wall
Chloroplasts
Chromatin/
chromosomes
Chromatin is the uncondensed form of DNA and proteins, while chromosomes are the condensed, visible structures formed from chromatin during cell division
Chromatin: Regulates gene expression, DNA packaging.
Chromosomes: Carry genetic information, ensure accurate transmission during cell division.
Describe the differences between plant and animal cells?
Cell Wall:
Plant Cells: Have a cell wall made of cellulose.
Animal Cells: Lack a cell wall.
Chloroplasts:
Plant Cells: Contain chloroplasts for photosynthesis.
Animal Cells: Lack chloroplasts.
Vacuoles:
Plant Cells: Have one large central vacuole.
Animal Cells: Have smaller or multiple vacuoles.
Shape:
Plant Cells: Often fixed rectangular or square shape.
Animal Cells: Varied shapes, often roundish.
Explain the structure of phospholipids
Phospholipids have a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tail.
In water, phospholipids spontaneously arrange themselves into a double layer with the heads facing outward towards the watery environment and the tails tucked inward, away from water.
Fluidity/ Selectively permeability
The membrane is constantly in motion, with phospholipids moving laterally within the bilayer.
This fluidity allows for small molecules like oxygen and carbon dioxide to pass through the membrane easily.
The membrane is selectively permeable, meaning it allows some molecules to pass through while blocking others.
Small molecules and certain proteins help transport materials across the membrane
What are some roles of a membrane in a cell
- Isolation of enzymes
- Transportation of materials/substances
- Make proteins and lipids
- Cell communication
Why are cells quite small? OR Why are we multicellular?
The size of a cell is limited by its ability to obtain the materials needed for survival and its ability to get rid of waste.
The cell’s VOLUME determines the amount of materials it needs, but its SURFACE AREA determines how much it can obtain, since all these materials must pass through the cell membrane.
Particle Theory
All particles move randomly due to their kinetic energy (which is related to their temperature!!)
If the particles are in a FLUID, this movement will cause them to naturally get farther apart and spread out within their available volume.
This behaviour is known as DIFFUSION
Diffusion
the net movement of materials from an area of high concentration to an area of low concentration.
concentration is calculated by the number of particles of a substance present in a particular volume.
Equilibrium: Diffused evenly
Factors affecting the speed of Diffusion
Temperature
Distance Travelled
Mass of the particle
Density of the medium
Concentration Gradient
Diffusion through Membrane:
A molecule can diffuse through the membrane if it is small enough to fit between the spaces in between phospholipids and proteins.
It is non polar so it is able to go between fatty acids tails.
ONLY CO2 and O2 can do this!
Passive Transport
- No energy is required
- Uses natural movement of molecules of particles to move them in and out of cells
*Diffusion is the most simplest form of passive transport
Facilitated Transport
- Uses membrane proteins to help move materials
a) Osmosis - Using the movement of water such as aquaporins.
Because water is polar it can not use simple diffusion
Facilitated Diffusion
Uses transport proteins in the membrane to move a variety of molecules in and out of cells.
Each protein can move ONLY its target molecule. (specific)
Each molecule must move from high to low concentration.
The cell does not use any additional energy to do this.
i) Channel Proteins - create a “tunnel” for molecules to travel through.
ii) Carrier Proteins - change shape
Active Transport
- Uses energy to move materials across the membrane
- Used when particle is too large to move or theres too many particles to move. Or when particles are being moved against their concentration gradient (low conc. to high)
Primary and Secondary Active Transport
Primary - the transport protein itself uses the energy released by the ATP molecule to transport the particle.
Secondary - the transport protein uses a type of potential (stored) energy to transport the particle.
This potential energy is in the form of a concentration gradient of some other particle
Example: Sodium Potassium Pump
Sodium Potassium Pump
The sodium-potassium pump works like a tiny pump in our cells. It moves sodium (Na⁺) and potassium (K⁺) ions across the cell membrane, against their concentration gradients, using energy from ATP
- The pump binds three sodium ions inside the cell.
- ATP provides energy to change the shape of the pump, moving the sodium ions outside the cell.
- The pump then binds two potassium ions from outside the cell.
- This triggers another shape change, releasing the potassium ions inside the cell.
- The pump is now ready to start the cycle again.
Antiporters vs Symporters
Antiporters: Antiporters are proteins that move two different types of molecules across a cell membrane in opposite directions. where one molecule goes in while another comes out. For example, the sodium-potassium pump is an antiporter that moves sodium ions out of the cell while bringing potassium ions into the cell.
Symporters: proteins that move two different types of molecules across a cell membrane in the same direction. where both molecules move together in one direction. For example, the sodium-glucose symporter moves both sodium ions and glucose molecules into the cell together.
Bulk Transport/Cytosis
type of active transport that uses the ability of the cell membrane to “pinch off” to create vesicles, or to fuse vesicles with the membrane. (Does require energy)
Types of Endocytosis:
- Bringing Material into cell (Endo = Enter)
1. Pinocytosis - This is like the cell drinking. It takes in fluids along with any dissolved molecules by forming small vesicles
2. Receptor Mediated Endocytosis - uses recognition proteins on the cell surface to select specific molecules to be brought into the cell.
3. Phagocytosis - This is like the cell eating something. It engulfs large particles, such as food or bacteria, and forms a vesicle to bring them inside. used by amoeba and other protists to bring in food particles.
Exocytosis
- Exiting the cell (Exo = Exit)
- The process of exocytosis allows the cell to secrete materials into its surroundings.
-These materials can include wastes, hormones, enzymes, or other substances, like the waxy coating on leaves.
-Often it is the vesicles packaged by the Golgi body which undergo exocytosis.
Types of Concentration
- Higher concentration: Hypertonic
- Lower concentration: Hypotonic
- Equal Concentration: Isotonic
Channel Proteins
- Proteins that can pass through water because their channels are hydrophilic
Aquaporins
Vesicular Transport
When vesicles help to move molecules into a cell
Plasmodesta
Plants only
Function: Channels between plant cells for sharing nutrients and communication.
Gap junctions
Animals
Function: Channels between animal cells for communication.
Tight Junctions
Animals
Function: Seals between animal cells to prevent leakage of fluids.
Desmosomes
Function: Spot welds between animal cells for strength and stability.
Cell connections…..
These connections help cells in plants and animals communicate, stay connected, and maintain their structure.
