Biology- Cells Flashcards
Prokaryotes vs. Eukaryotes
- Prok. do not have a nucleus
- Hereditary material exists as single “naked” DNA molecule w/o eukaryote chromosome’s DNA proteins]
- Prokaryotic ribosomes are smaller
- Cell walls of bacteria and cyanobacteria, when present are constructed from peptidoglycans. The cell walls of archaebacteria contain various polysaccharides, but not peptidoglycans, cellulose or chitin
- Flagella, when present in prok, are not made of microtubules
Extracellular Matrix
found in animals, in the area between adj. cells. The area is occupied by fibrous structural proteins, adhesion proteins, and polysaccharides secreted by the cells.
- provides mechanical support and helps bind adj. cell together
- the most common substance in this region is the protein collagen
Cell junctions
serve to anchor cells to one another or to provide a passageway for cellular exchange
spindle apparatus
guides the movement of chromosomes during cell division
hypotonic
a lower concentration of solutes
Nucleosomes
basic unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound in sequence around eight histone protein cores
Carrier Proteins
bind to specific molecules which are then transferred across the membrane after the carrier protein undergoes a change of shape.
Ex. glucose goes through cell through carrier proteins
Transmembrane Proteins
proteins that appear at both surfaces
Flower parts
numbers of petals, sepals, stamens, and other flower parts
Dicots: in 4s, 5s, or multiples thereof
Monocots: in 3s or multiples thereof
Ribosomes
subunits are manufactured in the nucleus and consist of RNA molecules and proteins
-(cytoplasm) ribosomes assist in the assembly of amino acids
Centrosome
a pair of centrioles located outside the nuclear envelope gives rise to the microtubules that make up the spindle apparatus used during cell division
Fluid Mosaic Model
the mosaic nature of scattered proteins within a flexible matrix of phospholipid molecules
Vesicular Transport
uses vesicles or other bodies in the cytoplasm to move macromolecules or large particles across the plasma membrane
- Exocytosis
- Endocytosis
- Phagocytosis
- Pinocytosis
- Receptor-mediated endocytosis
Adhesion Proteins
attach cells to neighboring cells or provide anchors for the internal filaments and tubules that give stability to the cell
Peripheral Proteins
proteins attached loosely to the inner or outer surface of the membrane
Animal Cell Junctions
- Anchoring junctions-are protein attachments between adj. animal cells.
- desmosomes- consists of proteins that bind adj. cells together, providing mechanical stability to tissues
- Tight junctions-tightly stitched seams between animal cells (makes a seal that prevents passage of materials).
- tight junctions-are characteristic of cells lining the digestive tract where materials are required to pass through cells
- Communication junctions
isotonic
an equal concentration of solutes relative to another region
Plasma Membrane (cell membrane)
double phospholipid membrane (lipid bilayer w/ polar hydrophilic heads & nonpolar hydrophobic tails)
Recognition Proteins
gives each cell type a unique identificaiton
- glycoproteins due to short polysaccharide chains (oligosaccharides) attached. The oligosaccharide extends away from membrane surface
prokaryotes
generally consist only of a plasma membrane, a DNA molecule, ribosomes, cytoplasm, and often a cell wall.
cytoskeleton
internal structure of the cytoplasm
Endoplasmic Reticulum
consists of stacks of flattened sacs involved in the production of various materials
- Rough ER creates glycoproteins by attaching polysaccharide groups to polypeptides as they are assembled by the ribosomes
- Smooth ER synthesis of lipids and hormones; (liver) breakdown of toxins, drugs, and toxic by-products
Cytosol
fluid matrix, which consists of water and dissolved substances such as proteins and nutrients
Chromatin
when DNA is spread out within the nucleus as a threadlike matrix
Leaf Venation
the pattern of veins in leaves
Dicot: netted (branching pattern)
Monocot: parallel
Communicating Junctions
passageways between cells that allow the transfer of chemical or electrical signals
- Gap junctions- narrow tunnels between animal cells that consist of proteins called connexins
- Plasmodesmata- narrow channels between plant cells.
Nucleus
bounded by nuclear envelope, consisting of phospholipid bilayers
- contains DNA
- nucleoli
-serves as the site for the separation of chromosomes during cell division
Desmotubule
found in the plasmodesmata; a narrow tube of endoplasmic reticulum is surrounded by the cytoplasm and the plasma membrane and passes through the channel
Receptor Proteins
provide binding sites for hormones or other trigger molecules. In response, to the hormone or trigger molecule a specific cell response is activated
Vesicular Transport
Exocytosis
the process of vesicles fusing with the plasma membrane and releasing their contents to the outside of the cell
Collenchyma
- have only primary cell walls
- irregularly shaped due to uneven thickening of cell wall.
- Their cell walls (thick/flexible) can stretch and elongate even at maturity so they can function in support
Vesicular Transport
Endocytosis
describes the capture of a substance outside the cell when the plasma membrane merges to engulf it.
- phagocytosis “cellular eating”- occurs when undissolved material enters the cell such as a white blood cell
- pinocytosis “cellular drinking”- occurs when dissolved substances enter the cell
- receptor-mediated- a form of pinocytosis, occurs when specific molecules in the fluid surrounding the cell bind to specialized receptors
- proteins that transport cholesterol in blood and certain hormones use this
Active Transport
movement of solutes against a gradietn and requires the use of energy (especially ATP).
- transport proteins in the plasma membrane transfer solutes such as small ions (Na+, K+, Cl-, H+), amino acids, and monosaccharides
Passive Transport
processes which describe the movement of substances from regions of higher to lower concentrations (down a concentration gradient) and do not require use of energy
- Simple diffusion
- Osmosis
- Dialysis
- Plasmolysis
- Facilitated diffusion
- Countercurrent exchange
Passive Transport
Countercurrent exchange
describes the diffusion of substances between two regions in which substances are moving by bulk flow in opposite directions
Passive Transport
Simple Diffusion or Diffusion
the net movement of substances from an area of higher concentration to an area of lower concentration
Parenchyma Cells
most common component of ground tissues
- thin primary cell walls
- totipotent
- typically unspecialized but they function in storage (such as starch granules), photosynthesis (help out in leaves), and secretion
Mitochondria
carry out aerobic respiration, a process in which energy (in the form of ATP) is obtained from carbohydrates
Integral Protein
proteins that are amphipathic and extend into the membrane
What is found in the extracellular region of a cell?
cell walls and the extracellular matrix
Porins
allow passage of certain ions and small polar molecules through membranes.
Ex. aquaporins (kidney and plant roots) found in the plasma membrane, increase passage rate of H2O molecules
Glyoxysomes
break down stored fatty acids to help generate energy for growth
Bulk flow
collective movement of substances in the same direction in response to a force or pressure
Na+ - K+ Pump
uses ATP to maintain higher concentrations of Na+ and K+ on opposite sides of the plasma membrane
Transport Proteins
uses energy (ATP) to transport materials across the membrane
Root
form of root
Dicot: taproot (a large single root)
Monocot: fibrous system (a cluster of many fine roots)
What are some features of the plasma membrane?
- phosholipid membrane
- proteins
- cholesterol
- glycocalyx
Channel Proteins
provide open passageways through the membrane for certain hydrophilic (water-soluble) substances such as polar and charged molecules
Cilia
short, many, and move w/ a back and forth movement; arranged in a “9+2” array
- line the respiratory tract and sweep away debris
Passive Transport
Facilitated Diffusion
the diffusion of solutes or water through channel proteins
NOTE: water can pass through the plasma membrane w/o the aid of specialized proteins, but aquaporins increase the rate of transfer by facilitated diffusion
Microtubules, intermediate filaments, and microfilaments
three protein fibers of decreasing diameter, respectively. All are involved in establishing the shape of or in coordinating movements of the cytoskeleton
- Microtubules- made of the protein tubulin and provide support and motility for cellular activities; found in the spindle apparatus and in flagella/cillia
- Intermediate filaments- provide support for maintaining the shape of the cell
- Microfilaments- made of the protein actin and are involved in cell motility; found in muscle cells and in cells that change shape like phagocytes
Golgi Apparatus
modify and package proteins and lipids into vesicles
Passive Transport
Dialysis
diffusion of solutes across a selectively
Glycocalxyx
a carbohydrate coat that covers the outer face of the cell wall of some bacteria and the outer face of the plasma membrane of certain animal cells
-may have adhesive properties, provide barriers to infection,or may be markers for cell-cell recognition
Cotyledons
storage tissue that provides nutrition to the developing seedling
Dicots: 2 cotyledons
Monocots: 1 cotyledon
Ion Channels
allow the passage of ions across the membrane
- gated channels (in nerve/musclecells) open/close in response to stimuli (chemical/electrical) to allow passage of specific ions (Na+ and K+)
- can be voltage-gated (respond to membrane potential difference), ligand-gated (chemical binds and opens channel), or mechanically-gated (respond to pressure, vibration, temp.)
Are centrioles and basal bodies found in plants?
Plant cells lack centrioles and only lower plants (such as mosses and ferns) w/ motile sperm have flagella and basal bodies
Gymnosperm (largest group of living gymnosperms: conifers)
woody cone-bearing plant
Passive Transport
Plasmolysis
the movement of water out of a cell (osmosis) that results in the collapse of the cell (especially plant cells w/ central vacuoles)
Ground tissues include what three kinds of cells?
- Parenchyma- synthesis/ storage of sugars and other compounds
- Sclerenchyma- support (fixed in size)
- Collenchyma- support (expandable in size)
Chloroplasts
carry out pohtosynthesis, the plant process of incorporating energy from sunlight into carbohydrates
Passive Transport
Osmosis
the diffusion of water molecules across a selectively permeable membrane
Basal bodies
at the base of each flagellum and cilium and appear to organize their development. Both centrioles and basal bodies are made up of 9 triplets of microtubules arranged in a circle.
Hypertonic solute concentrations
higher concentration of solutes
Sclerenchyma Cells
- has both primary and secondary cell walls that are thicker than collenchyma, are lignified, and contain cellulose.
- Usually dead at maturity and function well for support
- There are four types: fibers, sclereids, tracheids, and vessel elements
Chromosomes
when the cell begins to divide, the chromatin condenses into rod-shaped bodies
Peroxisomes
break down varioius substances including hydrogen peroxide (H2O2), fatty acids, and amino acids
- common in liver and kidney cells
- in plants, modify by-products of photorespiration
phagocytes
white blood cells that wnader throughout the body attacking bacteria and other foreign invaders
Vesicles
fluid-filled, membrane-bound bodies.
- transport vesicles- move materials between organelles or between organelles and the plasma membrane
Cholesterol
distributed throught the phospholipid bilayer that provide some rigidity to the plasma membranes of animal cells
Plants (sterols)
Lysosomes
vesicles from Golgi Apparatus that contain digestive enzymes
- break down food
- cellular debris and forein invaders
- do not occur in plants
- a low pH is maintained inside the lysosomes
Vascular bundles
arrangement of bundles of vascular tissue (xylem and phloem) in stems
dicots: organized in a circle
monocots: scattered
Phospholipid membrane
- selectively permeable
- only small, uncharged, polar molecules (H2O, CO2) and hydrophobic molecules (nonpolar like O2; hydrocarbons) freely pass
- No ions; large polar molecules
Plant Cells vs. Animal Cells
Plants- have cell walls, chloroplasts, and central vacuoles
Animals- have lysosomes, centrioles, and cholesterol
Ground tissue
fills up everytheing around the dermal and vascular tissues. In the stems, GT is found in the pith and cortex. In the leaves, GT is found in teh mesophyll.
- Most photosynthesis and carbohydrate storage takes place here
Cell walls
found in plants, fungi, protists, and bacteria
- in plants, the cell wall mainly consists of cellulose, a polysaccaride made from a B-glucos
- in fungi, the walls are usually made of cellulose or chitin (a modified polysaccharide differing from cellulose in that one of the hydroxyl groups is replaced by a group containing nitrogen)
Angiosperms (flowering plants)
divided into two groups:
- dicotyledons (dicots)
- monocotyledons (monocots)
Flagella
long, few, and move in a snakelike motion. Consist of microtubules arranged in a “9+2” array- nine pairs (doublets) of microtubulles arranged in a circle surrounding a pair of microtubules
- propel sperm
Animal Cell
Plant Cell
Vacuoles
fluid-filled, membrane-bound bodies
- food vacuoles- temporary receptacles of nutrients. Food vacuoles often merge w/ lysosomes, whose digestive enzymes break down the food
- storages vacuoles- in plants store starch, pigment, and toxic substances (nicotine for example)
- central vacuoles- large bodies occupying most of the interior of certain plant cells. When fully filled, they exert turgor, or pressure, on the cell walls, thus maintaining rigidity in the cell. They also store nutrients and carry out functions otherwise assumed by lysosomes in animal cells
- contractile vacuoles- specialized organelles in single-celled organisms that collect and pump excess water out of the cell.
