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56 terms

parts of a cell, and cell transport

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Cytoplasm
- Collective term for all of the contents of the cell outside the nucleus, but within the cell membrane
Supports the organelles in the cell (jelly - like)
contained in animal and plant cells
Lysosome
- Membrane - bound sacs.
- Contain enzymes used to break down molecules, especially proteins, lipids or carbohydrates
- can also transport undigested material to the cell membrane for excretion from the cell
- Can cause the cell to break down if broken (allowing the enzymes to be released which will digest the cell)
Sack of digestive enzymes (breakdown of food and dead organelles)
contained in animal cells only
vesicle
- Membrane - bound sacs used for transporting materials
Transport of materials in and out of cells (small vacuole)
contained in animal cells only (contain many)
Vacuole
- Membrane - bound sacs used for storage, digestion and waste removal
used mostly for water storage and balance
contained in plant cells only, most plants contain only one large vacuole
Cell membrane (plasma membrane)
-A double - layared membrane made of phosholipids with proteins embedded within it
- surrounds the cell
- semi - permeable to allow the passage of materials in and out of the cell
Protective cell envelope controlling what comes in and out of the cell (selectively permiabe)
contained in animal and plant cells
Chloroplast
- One of a group of organelles called plastids
- Found only in plant cells and algae
- contains the green pigment chlorophyll
- convert energy from the sun into a stored form of chemical energy called glucose
Site of photosynthesis (provides food for cell)
Endoplasmic reticulum
- A 3 - dimensional network of tubes, made by one continuous membrane (an extension of the nuclear membrane)
- Can be rough (if ribosomes are attached) or smooth
- Serves as the cell's transportation system
- Also used to store substances, especially proteins, until they are completed
Transport "highway"
contained in both plant and animal cells
Ribosome
- Small, spherical organelles that can be free - floating in the cytosol, or found attached to the endoplasmic reticulum
- Make up 25% of the total mass of the cell
- Responsible for the manufacture of proteins within the cell
contained in both plant and animal cells
Golgi body (golgi complex/apparatus)
- Composed of a stack of flattened sacs
- Made up of a series of double membranes
- Responsible for packaging proteins for storage or export out of the cell (modifies, sorts, and exports proteins)
contained in both plant and animal cells
Mitochondrion
- Organelle that performscellular respiration in a eukaryotic cell
"power house" of the cell (provides cell with energy)
contained in both plant and animal cells
Nuclear membrane (nuclear envelope)
- A double membrane that surrounds the nuceus
- Contains pores that allow the passage of materials in and out of the nucleus
Porous envelope surrounding the nucleus directing materials in and out
contained in both plant and animal cells
Nucleus
- "control centre" of the cell
- Contains DNA, the hereditary material of the cell
- RNA is transcribed here
- Consists of the nuclear envelope, chromatin and nucleolus
contained in both plant and animal cells
Nucleolus
- Densely packed ball of DNA, RNA and protein
- Visible in the cell only when the cell is not dividing
- Used to make ribosomes
- In the nucleus
contained in both plant and animal cells
Chromatin
- Long, thread - like strands of DNA
- Thicken and coil into chromosomes during cell division
- There are a set number of these strands for each species ( in humans there are 46)
Genetic material
contained in both, plant and animal cells
Centriole
- Pair of cylindrical organelles found near the nucleus
- Each one composed of nine tubes, each tube made up of three microtubules
- The cylinders lie at right angles to one another
- Involved in cell division (needed to make spindle fibers)
contained only in animal cells
Microtubules
- Of variable length
- Used to make spindle fibres during cell division
- Also used to make cilia and flagella in unicellular organisms
Cell wall
- Made up of cellulose fibres which gives it a rigid structure
- Provides support and protection to the cell
- Surrounds the cell membrane
contained in plant cells only
Cytosyl
- A clear, structure less fluid
- Composed mainly of water, but does contain free - floating molecules and other dissolved substances
Contained in both, plant and animal cells
Cell theory
Assumptions that cells compose all living things and arise only from pre - existing cells
Chromosomes
Structure in the nucleus of a eukaryotic cell that carries genes, formed when chromatin condenses
Cilia
Hair - like structures that project from a cell and beat to produce movement
Cytoskeleton
Network of fine protein fibres that supports a eukaryotic cell
Flagella
Long whip - like cellular projections that beat to produce movement
photosynthesis
Use of light energy to convert carbon dioxide and water into carbohydrates, carried out by the chloroplasts of plants and some protists
Phospholipid bilayer
Double layer of outward - facing phosphates and inward - facing fatty acids that form a cell membrane
Fluid mosaic model
Description of the arrangement of protein molecules in the fluid double layer of the cell membrane
Hydrophilic
describes a molecule that dissolves in water
Hydrophobic
describes a molecule that does not dissolve in water
Phospholipid
Lipid found in a cell membrane; formed by two hydrophobic fatty acids and a hydrophilic head containing a phosphate group and a nitrogen - containing group
Glycoprotein
protein combined with a carbohydrate, embedded in the cell membrane, that functions in cell communication or recognition
Glycocalyx
Sugar chains that attach to communication or recognition proteins, serving as their binding sites. The glycocalyx can also lubricate cells and act as an adhesion layer for them
Cholesterol
Compound found in some animal tissues that helps maintain the fluidity of the cell membrane
Diffusion (brownian motion)
The spontaneous movement of particles from an area of higher concentration to an area of lower concentration.
- Involves solids and gases
e.g. gas exchange in lungs
concentration gradient
Difference within a given area between the highest and lowest concentration of a particular chemical substance
Integral protein
Protein embedded in the cell membrane that performs a specific function.(recognition)
Peripheral protein
A protein that temporarily adheres to the biological membrane, either to the lipid bilayer or to integral proteins by a combination of hydrophobic, electrostatic, and other non-covalent interactions. (Structural support)
Proteins
Large molecule formed by amino acids that directs chemical reactions in the body.
The four functions of proteins:
Structural support - often when attached to parts of the cell's scaffolding or cytoskeleton
Recognition - binding sites on some proteins can serve to identify the cell to other cells, such as those of the immune system
Communication - receptor proteins, protruding out from the plasma membrane, can be the point of contact for signals sent to the cell via traveling molecules, such as hormones
Transport - Proteins can serve as channels through which materials can pass in and out of the cell
Factors responsible for the movement of materials in and out of the cell
- Polarity
- Energy
- Size of the molecule/ion
- Pressence of transport proteins/receptors
- Fluidity of cell membrane
- Concentration of gradient
Selectively permeable
- Only certain ions/molecules have the ability to penetrate through the cell membrane.
e.g. non polar solutes and small polar molecules can easily pass through
Passive transport
- No energy required
- materials move from an area of high concentration to an area of low concentration. (along the concentration gradient)
- the movement is random
Types:
diffusion, osmosis, and facilitated diffusion
Osmosis
Passive movement of water through a selectively permeable membrane
Turgor pressure
Osmatic pressure exerted by the contents of the plant cell against the cell wall
Plamsolysis
Contraction of the cytoplasm as a result of loss of water causing the vacuole to shrink
Facilitated diffusion
Diffusion of solutes across a membrane with the help of a transport protein (no energy required)
Channel proteins
These transport proteins simply provide a channel for ions
Carrier proteins
Are substrate specific.
bind to solute and physically move them across membranes(no energy is used)
Active transport
- requires energy from ATP
- materials move against the concentration gradient (from low concentration to high concentration)
e.g. sodiom potassium pump
Sodium potassium pump
- Specialized protein in a cell membrane that transports sodium ions out of a cell and potassium ions into a cell against their concentration gradients.
- located in nerve cells and critical to their function
- nerve cells must maintain a higher concentration of sodium ions outside the cell, and potassium ions inside the cell
Endocytosis
- Particles enter cell
- Material collects in pocket of cell membrane
- Pocket pinches inwards forming a vesicle
- require energy from ATP
- 3 types:
phagocytosis, pinocytosis, receptor - mediated endocytosis
Exosytosis
- Particles exit the cell
- Vacuole/vessicle fuses with cell membrane
- contents released to the outside
Phagocytosis
- Cell "eating"
- Intake of large solids, food, bacteria
- Forms a vacuole
- non - specific
e.g. white blood cells attacking invaders
Pinocytosis
- Cell "drinking"
- Intake of small droplets of liquid and tiny particles
- Forms a vessicle
- non - specific
Receptor - mediated endocytosis
- Molecule binds to receptor protein
- Complex migrates to "coated pit"
- "coated" pit pinches inwards forming a vacuole
- specific
Isotonic solution
- The solution has the same water concentration as the cell
Animal Cell:
- water moves in and out of the cell at equal rates
- no net movement of water
- normal state for animal cells
Plant Cell:
- Same conditions and net movement of water as in animal cells
- Cell is flacid (limp)
- Plant wilts
Hypotonic solution
- The solution has a higher water concentration, than inside the cell
Animal cell:
- Greater water concentration outside the cell
- More water enters the cell than leaves
- Cell swells and breaks (lyses)
Plant cell:
- Same conditions and net movement as animal cells.
- Cell swells
- Cell wall pushes back
- normal state for plant cells
Hypertonic solution
- The solution has a lower water concentration, than inside the cell
Animal cell:
- lower water concentration outside the cell
- more water leaves the cell than enters
- cell shrinks and shrivels
- cell may die
Plant cell:
- same conditions and net movement as in animal cells.
- cell membrane pulls away from the cell wall
- plasmalysis
-cell dies