Biology C1/2 Flashcards
Cell Theory
1) All living things are made up of one or more cells
2) Cells are the smallest functional unit of life
3) All cells are produced by the division of other pre-existing cells
Robert Hooke
The first person to observe and describe cells
Antonie van Leeuwenhoek
Observed the first living cells and called them “animalcules”
Botanist Matthias Schleiden
Stated that plants were made up of cells
Zoologist Theodor Schwann
Stated that animals were made up of cells
Robert Brown
Discovered the nucleus in plant cells
Francesco Redi
Disproved the theory of spontaneous generation
Louis Pasteur
Proved beyond a reasonable doubt that spontaneous generation of life does not now occur
Rudolph Circhow
Observed cells dividing and stated that new cells are formed by the division of pre-existing cells
Light Microscope
Visible light is passed through a specimen, and then one (simple) or two (compound) glass lenses. The lenses refract the light
Transmission Electron Microscope
A beam of electrons is passed through a very thin section and electrons that pass through fall on photographic film - produces clear images of interior
Scanning Electron Microscope
Electrons reflected off a specimen covering with an electron-dense material (gold) - produce 3-D image of the surface
Prokaryotic Cells
- Smaller than eukaryotic cells
- Lack membrane-bound organelles
- Earth’s first inhabitants
Eukaryotic Cells
- Larger than prokaryotic cells
- Have a true nucleus and membrane-bound organelles\
- Evolved from prokaryotic cells
- Involves animal and plant cells
Organelles
Membrane-bound structures inside eukaryotic cells that have specialized functions
Cell Wall
Rigid outer layer made up of cellulose that maintains the cell’s shape and protects the cell from mechanical damage. Only in plant cells.
Cell Membrane
Flexible phospholipid bilayer surrounding the cell, that serves as a selectively permeable barrier between he inside and outside of the cell
Cytoplasm
A semifluid, jellylike substance containing dissolved substances, in which organelles and other components are found
Nucleus
Contains the DNA, and directs all cellular activity. Densely stained part is nucleolus, where ribosomes are produced
Nuclear Envelope
Double-membrane surrounding the nucleus, that has nuclear pores to allow transport to allow transport of materials into and out of the nucleus
Ribosomes
Small complexes that translate genetic information (DNA) into proteins
Rough Endoplasmic Reticulum (Rough ER)
Studded with ribosomes and packages and transports secretory protein. Connected with the nucleus
Smooth Endoplasmic Reticulum (Smooth ER)
Not studded with ribosomes, synthesizes lipids and packages them for transport to other parts of the cell
Golgi Apparatus
Recieve transport vesicles from the ER. ER products are modified and stored, then sorted, repackaged, and shipped to other destinations in the cell
Lysosomes
Membrane sacs containing digestive enzymes within an acidic environment. Used to breakdown food particles, kill infectious micro-organisms, and to recycle damaged or worn-out cell parts. Only in animal cells
Vacuoles
Membrane-bound sacs used for storage of food, water, mineral, and other substances. Plants have a large central vacuole that is important for storage and water regulation
Mitochondria
Has 2 membranes, the inner being highly folded. Where cellular respiration occurs to generate ATP
Chloroplasts
Has 2 membranes, containing flattened membranous sacs with chlorophyll. Where photosynthesis occurs, converting light energy into chemical energy
What is the plasma membrane made out of
The plasma membrane is composed of phospholipids, proteins, carbohydrates, and cholestrol
Phospholipids
- Have a phosphate head and two fatty acid tails
- Phosphate head is hydrophilic (polar)
Face out toward watery fluid - Fatty acid tails are hydrophobic (non-polar)
Face in toward interior of bilayer away from the water
Proteins
- Can be embedded in or attached to the phospholipid bilayer
- Transports specific substances into or out of the cell
Fluid Mosiac Model
- States that the membrane is a “fluid” structure with a “mosiac” of various proteins embedded in or attached to a bilayer of phospholipids
- Fluid because the components of the membrane are in constant motion
- Mosiac because proteins are embedded in the phospholipid bilayer
Cell Membrane Function
1) Gives shape and structure to the cell
2) Acts as a biological barrier, separating and protecting the cell from its surroundings
3) Regulates the movement of substances into and out of the cell
Selective Permeability
- Non-polar molecules are hydrophobic and can easily cross the lipid bilayer of the membrane
- Polar molecules are hydrophilic and have difficulty passing through the hydrophobic core of the membrane
- Charged molecules have a sphere of water molecules around them that prevents their passage through the membrane
- Large molecules don’t fit
Selective Permeability - Transport Proteins
- Channel: Hydrophilic channel that allows for polar and charged molecules to pass through
- Carrier: Holds onto certain molecules and changes shape to shuttle molecule across membrane
Passive Transport
Diffusion of a substance across a membrane with no energy investment; No energy since it moves down the concentration gradient because it represents potential energy
Diffusion
- Occurs across a cell membrane if there is a concentration gradient
- Each type of molecule diffuses along its own concentration gradient, independently of other molecules
- Only small, hydrophobic, uncharged solute molecules are able to diffuse through the phospholipid bilayer
Osmosis
- The diffusion of water across a selectively permeable membrane
- Occurs when a concentration gradient exists for solute molecules that cannot diffuse
- Water diffuses to balance the concentration
- Membranes have channel proteins called aquaporins that allow movement of water
Hypotonic
- Solute concentration of the solution is less than that of the cell
- Water enters the cell
- Animal cells swell and lyse
- In plant cells, uptake of water creates turgor pressure that pushes out on the cell wall and keeps the plane cells firm
Isotonic
- Solute concentration of the solution is the same as that of the cell
- No net movement of water
- Animal cells do best in isotonic environments
- Plant cells become limp because there is no turgor pressure
Hypertonic
- Solute concentration of the solution is more than that of the cell
- Water leaves the cell
- Animal cells become shriveled
- Plant cells undergo plasmolysis
Faciliated Diffusion
- Diffusion of solute particles across the membrane with help of transport proteins
- Transport proteins provide hydrophilic passageways that allow small, polar, molecules and ions to cross
Active Transport
- Uses energy (ATP) to move solutes against their concentration gradients
- Carrier proteins called “protein pumps” are the transport proteins involved
Bulk Transport
- Transportation of large molecules
- Large molecules must be packaged in vacuoles or vesicles in order to be transported across the membrane
- Requires ATP
Endocytosis
- The cell takes in material by forming new vacuoles/vesicles from the plasma membrane
- Plasma membrane sinks inward to form a picket. The picket deepens and pinches in, forming a vacuole/vesicle
Exocytosis
- The cell exports material by fusing vesicles with the plasma membrane
- A transport vesicle fuses with the plasma membrane and releasing the contents outside
