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