LO 3 Flashcards
Human cells ______ in size and shape
Vary considerably - 200 types and 100 trillion cells in the body
What is the basic composition of all human cells?
Cytoplasm, plasma membrane, organelles, nucleus
Describe the plasma membrane
It encloses the cytoplasm and forms the outer boundary, phospholipid bi-layer, selectively permeable, contains specialized proteins on surface
Describe cytoplasm
Internal ‘living’ material of cells, between plasma membrane and nucleus, contains cytosol (intracellular fluid), contains organelles
What are ribosomes responsible for?
Creating proteins (ribosomes often found on ER)
Describe the endoplasmic reticulum
Network of connecting sacs that carry substances through the cytoplasm
Describe golgi apparatus
Group of stacked, flattened sacs near the nucleus
Recieve substances from smooth ER via vesicles, then package, process, and transport substances to plasma membrane for release
Describe the mitochondria
Composed of inner and outer membranes, is the site if cellular respiration, contains one DNA molecule
Describe lysosomes
Membranous-walled organelles, resemble small sacs, contain digestive enzymes that can destroy microbes,
Describe centrioles
Fine, rod-shaped tubes that exist in a pair (at right angles) near the nucleus - vital in cell division
Describe microvilli
Finger-like projections on cell membrane that increase surface area
Describe cilia
Fine hair-like extensions on free or exposed surfaces of some cells - propel a cell or move substances (e.g mucus)
Describe flaggelum
Single projection extending from cell surface that creates propulsive movement (sperm)
What are the 4 layers of the nucleus?
- Nuclear membrane
- Nucleoplasm
- Nuleolus - produces ribosomes
- Chromatin granules - package DNA in a smaller volume to fit cell
What are the 2 methods of transportation across the cell membrane?
- Passive transport
- Active transport
Define passive transport?
Form of transport that does not require additional energy - results from movement down a concentration gradient (diffusion and filtration)
What are the 2 types of diffusion?
- Osmosis - diffusion of water when some solutes can’t cross membrane
- Dialysis - diffusion of solutes
Define osmotic pressure
The minimum pressure that must be applied to a solution to halt the flow of solvent molecules through a semipermeable membrane (osmosis)
Define isotonic
A solution with the same osmotic pressure as body fluids - no net movement
Define hypertonic
A solution with higher osmotic pressure than body fluids - water flows out of cell
Define hypotonic
A solution with lower osmotic pressure than body fluids - water flows into cell
Define filtration
Movement of water and small solutes through a membrane (high pressure to low pressure). High pressure on one side of membrane -hydrostatic pressure
Define hydrostatic pressure
The pressure exerted by a fluid at equilibrium at any point of time due to the force of gravity (e.g. during formation of urine by kidneys)
Active transport requires ______
Energy from ATP
Types of active transport include ______
- Ion pumps
- Phagocytosis and pinocytosis
Describe ion pumps
A protein complex in cell membrane called a carrier uses energy from ATP to move substances across cell membrane against their concentration gradient (Na-K, Ca)
Describe phagocytosis
Means ‘to eat’. It is a protective mechanism used to engulf and destroy bacteria
Describe pinocytosis
Means ‘to drink’. Cell can engulf or drink fluids/dissolved substances to incorporate those fluids into the cell
What is complimentary base pairing?
A-T and G-C are the only two combinations of nitrogen bases
What is a gene?
A segment of base pairs within DNA molecule that dictates the formation of enzymes and other proteins by ribosomes
What does RNA do?
Transfers genetic information from the nucleus to the cytoplasm
Describe transcription
DNA unwinds, Messenger RNA is created, each strand of mRNA duplicates a particular gene, mRNA passes form nucleus to cytoplasm to direct protein synthesis in ribosomes
Describe translation
It is protein synthesis. Ribosomes read mRNA while tRNA brings the correct amino acids, forming a protein strand
The period of time when the cell is not actively dividing is called _______
Interphase
Describe DNA replication
DNA unwinds and separates between base pairs, each side attracts complimentary bases until each strand is whole again
It precedes mitosis
What are the 4 stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
Describe what happens during prophase
- Chromatin granules organize into chromosomes
- Chromosomes form pairs of linked stands called chromatids, which are connected at the centromere
- Centrioles move to poles and spindle fibres form between
- Nuclear envelope disappears
Describe metaphase
- Chromatids align across the center of the cell
- Spindle fibres attach to each chromatid
Describe anaphase
- Centromeres break
- Separated chromatids are again called chromosomes
- Chromosomes are pulled to opposite ends of the cell
- Cleavage furrow develops - beginning of cytokinesis
Describe telophase
- Cell division is completed
- Nuclei appear in each daughter cell
- Nuclear envelope and nucleoli appear
- Cytoplasm and organelles divide equally - growth
What are the 4 main types of tissue?
- Epithelial tissue
- Connective tissue
- Muscle tissue
- Nervous tissue
Where do you find epithelial tissue and what does it look like?
- Covers body and lines parts, organs, and body cavities
- Continuous sheets of tightly pact cells with very little intercellular material (matrix) - anchored to a basement membrane
What are the 4 epithelial shapes?
- Squamous - flat and scale like
- Cuboidal - cube shaped
- Columnar - taller than wide
- Transitional - varying shapes that can stretch
How is epithelial tissue classified by arrangement of cells?
- Simple - single layer of same shaped cells
- Stratified - multiple layers (named according to shape of outer layer)
Where would you find simple squamous epithelium?
Alveoli of lungs, lining of blood and lymphatic vessels (good structure for transport)
Where can stratified squamous epithelium be found?
Surface of skin and mucous membranes
Where can simple columnar cells be found?
Lining the inner surface of stomach, intestines, and some areas of the reproductive tracts – creates mucous
Where can stratified transitional epithelium be found?
Areas subject to stress such as urinary bladder
What is unique about pseudostratified epithelium?
Each cell touches the basement – only appears stratified due to the shape of cells, but actually a single layer
Where can you find cuboidal epithelium?
Often specialized for secretory activity, found in tubules (like urine producing tubules of kidneys) or glands (endocrine system)
A ductless gland is ______ while glands with ducts are ______
- Endocine
- Exocrine
Describe connective tissue
- Most abundant in body
- Most widely distributed
- Connects, binds, and supports structures
- Protects and cushions organs and tissues
- Insulates (fat)
- Transports substances
Where is connective tissue found?
Skin, membranes, muscles, bones, nerves, and all internal organs
What are the 7 types of connective tissue
- Loose fibrous/ areolar - most widely distributed, glue that holds organs together
- Adipose (fat) - stores lipids/insulates
- Fibrous - strong and flexible bundles of white collagen fibers (e.g. tendons)
- Bone - one of the most specialized, building blocks called osteoms (haversian systems)
- Cartilage - chrondrocyte is cell type
- Blood - transportation function
- Hematopoietic - formation of blood and lymphatic cells - immunity
What are the 3 types of muscle tissue?
- Skeletal - attaches to bones via tendons, striations apparent under microscope, voluntary control
- Cardiac - forms walls of heart, involuntary contractions
- Smooth - forms walls of blood vessels and hollow organs (digestive tract, respiratory tubes), involuntary control
What is nervous tissue?
Provides rapid communication between body structures and control of body functions via nerve impulses
What comprises nervous tissue?
- Neurons
- Glia - supportive and connecting cells
______ refers to a cell that bursts in a hypotonic solution
Lysis
The shriveling of a cell in a hypertonic solution is called ________
Crenation
