Chapter 2 - Cell Functions Flashcards
Prokaryotes
- Found in bacteria
- Lack of membrane bound organelles
- Contains free floating DNA
- Has a plasma membrane, cell wall, ribosomes and flagella/cilia
- No nucleus, mitochondrion, E.R, Golgi,
Lysosomes or chloroplasts
Eukaryotes
- Found in complex organisms (non-bacterial)
- Complex structure
- Have membrane bound organelles
- DNA found in nucleus
Active Transport
The use of proteins powered by ATP to move molecules against a concentration gradient
Apoptosis
Programmed and controlled series events which lead to cell death. Messenger molecules bind to receptors causing cascade of events within cell. Enzymes are triggered to break down cell components (many organelles unaffected) as cell begins into bleb into apoptic bodies encased in plasma membrane. Blebs are enveloped through phagocytosis.
Carrier proteins
Proteins within the plasma membrane that assist with the
passage of other molecules across the membrane in
facilitated and active transport
Channel proteins
Proteins that form channels within the plasma membrane to
allow for the passage of hydrophilic substances across the
membrane
Chromatin
A complex of proteins and DNA in eukaryotic chromosomes
Chromosome
Structure composed of DNA and protein that contains along its length linear arrays of genes carrying genetic information; prokaryotes have one circular chromosome whereas eukaryotes have a number of linear chromosomes
Concentration Gradient
Difference in concentration across a boundary
Substances move from high to low
Cytoskeleton
A network of filaments within a eukaryotic cell that provides structural support, anchorage, shape, motility and a capacity to move and arrange organelles within a cell
Passive Diffusion
The movement of a dissolved substance from an area of high concentration to an area of low concentration; the process is
passive and does not require an input of energy
Exocytosis
A fusion of a vesicle with the plasma membrane so that its
contents can be expelled or secreted from the cell
Extra-cellular matrix (ECM)
Mixture of structural proteins and glycoproteins found in space between neighbouring cell that supports tissue structure
Flagellum
(pl. flagella) whip-like organelle of cells that enable movement
Golgi Apparatus
An organelle in eukaryotic cells that modifies proteins and lipids before exporting them inside vesicles from the cell.
Isotonic
When the solution outside and inside the cell contains the same concentration of solute particles. There is no net
movement of water molecules.
Lysosomes
A membrane-bound vesicle in eukaryotic cells containing enzymes which is involved in the breakdown and recycling of many types of molecules
Organelle
Specialised structure or compartment in a eukaryotic cell that has a specific function
Phagocytosis
A form of endocytosis in which solid material is engulfed by a plasma membrane and surrounded by a liposome within a cell.
Pinocytosis
The process by which liquid and small molecules are engulfed and taken into the cell enclosed in a membrane-bound vacuole (endocytosis)
Plasma Membrane
The insoluble boundary of the living cell that maintains the contents of the cell and regulates the movement of
substances in and out of the cell. All cells have a plasma membrane
Plasmolysis
Occurs when the plasma membrane is drawn away from the cell wall in plants owing to the loss of water from the cell by osmosis
Prokaryotic
Cell that lack a membrane bound nucleus and other membrane bound organelles; all bacteria are prokaryotic cells
Ribosomes
The site of protein synthesis in all cells, this organelle is not
bound by a membrane; a ribosome consists of two rRNA (ribosomal RNA) subunits that lock onto a mRNA molecule; the ribosome moves along mRNA to translate its code and link amino acids. Forming a polypeptide
Turgid
When water has entered plant cells by osmosis to the extent
that their swollen vacuole pushes the cell membrane against the cell wall
Vacuole
A cavity inside a cell bounded by a membrane; it takes up most of the interior of a mature plant cell and contains dissolved materials for storage and waste; in animal cells, vacuole sacs are small and isolate materials, such as toxins and proenzymes, from the protoplasm
Osmosis occurs in the direction
Low water concentration —> High
High solute concentration to low
What determines whether a substance is permeable to a plasma membrane.
IN Vs OUT
Charge of molecule
size of molecule
IN: small polar and non polar molecules (non-polar more readily allowed through)
OUT; Ions and large molecules polar ones
Simple diffusion Vs Passive Diffusion
Simple: Net movement of molecules down a concentration gradient without assistance of proteins
Passive: Net movement of molecules down a concentration gradient with or without assistance of proteins
Facilitated diffusion
Net movement of molecules down a concentration gradient with the assistance of carrier and channel proteins.
Active transport
Net movement of molecules through carrier proteins against concentration gradient using ATP to provide the energy.
Isotonic
Surrounding fluid concentration equal to fluid inside the cell.
Hypertonic:
Net water movement
The outside fluid is hypertonic to the cell if it has a higher concentration of solute than inside the cell.
Water moves out of cell
Hypotonic:
Net water movement
The outside fluid is hypotonic to the cell if it has a lower concentration of solute than inside the cell.
water moves into cell
What is bulk transport
Large macromolecules or clumps of molecules are transported across the plasma membrane in a vesicle.
Endocytosis;
Name for solid and liquid endocytosis
Endocytosis: Plasma membrane sinks inwards, encloses particles within endocytic vesicle which transports them through the cytoplasm.
Solid: Phagocytosis
Liquid: pinocytisis
Protein secretion pathway
- ) Polypeptide chain synthesised from a bound ribosome
- ) Protein enters lumen of rough ER and folds into 3D shape
- ) Proteins leave ER in vesicle.
- ) Vesicle received by Golgi apparatus (at the cis-face) where they are modified, often adding a carbohydrate group.
- ) Proteins leave Golgi apparatus in liposome (from the trans-face) and are shipped to the cells membrane and exported from the cell in exocytosis.
When are bound ribosomes used compared to free ribosomes?
Free ribosomes usually for proteins to be used within the cell.
Bound ribosomes: usually for proteins that will be secreted by the cell
Identifying:
Rough ER
Smooth ER
Golgi apparatus
Rough ER: Interconnecting tubules with bumps (ribosomes)
Smooth ER: Interconnecting smooth tubules
Golgi apparatus: Looks like smooth ER but in shape of a C
Purpose of smooth ER
involved in the production of lipids, including phospholipids and cholesterol
Free ribosomes vs bound ribosomes purpose
Free ribosomes = synthesis of proteins that are to used in the cell
Bound ribosomes= synthesis of proteins that will be exported
Sequence of protein synthesis to be exported
- ) mRNA used to transcribe amino acid sequence on ribosome bound to the rough ER.
- ) polypeptide sequence enter lumen of rough ER and is folded into its 3D functional shape
- ) Protein exits rough ER in vesicle and enters Golgi apparatus through endocytosis.
- ) here protein is introduced carbohydrate creating glycoproteins.
- ) exits Golgi in vesicle and exocytoses out of the cell to be delivered around the body
Purpose of rough endoplasmic reticulum
Polypeptide chain folded into 3D functional shape with aid of enzyme and is prepared for the addition of carbohydrates in the Golgi.
Centriole
A pair of cylindrical structures that made up of several tubes that form spindle during cellular division.
Cilia
Hair like projections on the surface on some cells.
Peroxisomes
Contain enzymes that destroy toxic materials such as hydrogen peroxide.
Difference between Plant and animal cells
Plant: Cell wall, Chloroplast, large vacuole
Animal: No cell wall, No Chloroplast, small vacuole
Endosymbiotic theory and evidence
Mitochondria and Chloroplast were life forms of their own that were enveloped by a eukaryotic cell and utilised for energy production.
Evidence:
- Both have a double membrane, one of the prokaryote and one of the hosts.
- Both have unique circular DNA, allowing the, to pass on genetic info as independent organisms
- both contain small ribosomes indicating they make their own proteins.
Discuss importance of membrane bound organelles
Allow for chemical environments which reactions can proceed with maximum efficiency. Allows cell to keep harmful reactions and substances contained
Contractile vacuole
Contractile vacuoles absorb excess water and wastes from a microorganism’s cell and excrete them into the environment by contracting.
