Exam 1 Flashcards
describe the chemical composition of the plasma membrane and relate it to membrane functions
phospholipid bilayer with hydrophobic interior and hydrophilic exterior act as a barrier to separate intracellular fluid from extracellular fluid (hydrophilic phosphate heads near the fluid) and holds cell together
membrane proteins act as selective barrier
cell theory
cell is structural and functional unit of life
structure = function
cells arise from pre-existing cells
plasma membrane
flexible outer boundary that acts as active barrier between intracellular and extracellular fluids; controls what enters and leaves the cell
membrane proteins
allow cell communication with environment and most have specialized functions
two types of membrane proteins
integral and peripheral
integral membrane proteins structure and function
firmly inserted into plasma membrane and most span the membrane
hydrophobic region interact w/lipid tails
hydrophilic region interacts w/water
function as transport proteins, enzymes, and receptors
peripheral proteins structure and function
loosely attached to surface of phospholipid bilayer and include filaments on extracellular surface for plasma membrane support
function as enzymes, motor proteins for shape changes during cell division/muscle contraction, and cell-to-cell connections
glycalyx structure and function
sugars (carbohydrates) sticking out of cell surface creating a pattern unique to each cell
biological markers for cell-to-cell recognition; allows immune system to recognize “self” vs foreigner
cytoplasm
cellular material located between plasma membrane and nucleus: cytosol, inclusions, and organelles
cytosol
gel-like solution made up of water and soluble molecules (proteins, salts, sugars)
inclusions
insoluble molecules that vary w/cell type
examples of inclusions
glycogen, granules, pigments, lipid droplets, vacuoles, crystals
cytoplasmic organelles
metabolic machinery of cell; can be membranous or non-membranous
membranous organelles
mitochondria, ER, golgi, peroxisomes, lysosomes
non-membranous organelles
ribosomes, cytoskeleton, centrioles
mitochondria structure/function
Structure: double membrane; inner membrane = cristae imbedded with membrane proteins inner membrane; contain own DNA, RNA, and ribosomes
Function: produce most of cells ATP via aerobic resp.
capable of cellular division (fission)
ribosomes structure/function
non-membranous organelles made up of protein and ribosomal RNA (rRNA); can be either free or membrane-bound (attached to rough ER)
PROTEIN SYNTHESIS!!! free ribosomes= synthesis of soluble proteins functioning in cytosol; membrane bound= synthesis of intramembrane proteins, lysosome proteins, and proteins to be exported from the cell
rough endoplasmic reticulum structure/function
series of parallel, interconnected cisterns continuous with the outer membrane; contains ribosomes
synthesize/modify proteins; package in vesicles to be sent to golgi
what types of molecules are synthesized in the rough ER
proteins that will be secreted from the cell
plasma membrane proteins and phospholipids
structure/funciton smooth ER
network of looped tubules continuous w/rough ER; contains enzymes w/in its plasma membrane
Enzymes w/in smooth ER perform:
- Lipid metabolism; cholesterol and steroid-based hormone synthesis; making
lipids for lipoproteins
- Absorption, synthesis, and transport of fats
- Detoxification of certain chemicals (drugs, pesticides, etc.)
- Converting of glycogen to free glucose
- Storage and release of calcium
Sarcoplasmic reticulum
specialized smooth ER found in skeletal and
cardiac muscle cells
golgi apparatis structure/function
Stacked and flattened membranous cistern sacs
Modifies, concentrates, and packages proteins and lipids received from rough ER
three steps of golgi protein packaging
- Transport vesicles from ER fuse with cis (inner) face of Golgi
- Proteins or lipids taken inside are further modified, tagged, sorted, and packaged
- Golgi is “traffic director,” controlling which of three pathways final products will
take as new transport vesicles pinch off trans (outer) face
three possible pathways of final transport vesicle from the golgi
– Pathway A: Secretory vesicles containing proteins to be used outside of cell
fuse with plasma membrane and exocytosis contents
– Pathway B: Vesicles containing lipids or transmembrane proteins fuse with
plasma membrane or organelle membrane, inserting contents directly into
destination membrane
– Pathway C: Lysosomes containing digestive enzymes remain in cell, holding
contents in vesicle until needed
peroxisomes structure/function
Membranous sacs containing powerful detoxifying substances that neutralize toxins and play a role in breakdown and synthesis of fatty acids
free radicals
toxic, highly reactive molecules that are natural by-products of
cellular metabolism; can cause havoc to cell if not detoxified
lysosomes structure/function
Spherical membranous bags containing digestive enzymes (acid hydrolases)
– Considered “safe” sites because they isolate potentially harmful intracellular
digestion from rest of cell
– Digest ingested bacteria, viruses, and toxins
– Degrade nonfunctional organelles
– Metabolic functions: break down and release glycogen; break down and release Ca2+
from bone
– Intracellular release in injured causes cells to digest themselves (autolysis)
cytoskeleton structure and function
Elaborate network of rods that run throughout cytosol; can be either Microfilaments, Intermediate filaments, or Microtubules
rods link to to other strucutres via proteins; cell movement
Microfilaments structure/function
Thinnest of all cytoskeletal elements made of semi-flexible strands of protein actin
strengthen cell surface and can be involved in cell motility, changes in cell shape, or endocytosis and exocytosis
Intermediate filaments structure/function
Size is in between microfilaments and microtubules
Tough, insoluble, ropelike protein fibers composed of tetramer (4) fibrils twisted together, resulting in one strong fiber
Help cell resist pulling forces; act as internal guy-wires
microtubules structure/function
Largest of cytoskeletal elements; consist of hollow tubes composed of protein
subunits called tubulins, which are constantly being assembled and
disassembled; Most radiate from centrosome
Determine overall shape of cell and distribution of organelles: keep organelles in place and are used as roads by motor proteins
centrosome
located near the nucleus containing granular matrix and centrioles
microtubule organizing center
centriole structure/function
barrel shaped microtubular organelles
source of radiation of newly assembled microtubules; form basis of cilia and flagella
nucleus strucutre and function
largest cell structure; contains DNA; consists of Nuclear envelope, Nucleoli, and Chromatin
uninucleate
one nucleus (most cell types)
mulitnucleate
many nuclei; found in skeletal muscle, certain bone cells, and some liver cells
anucleate
no nucleus
mature RBC
pathway of secretion
- Rough ER synthesizes proteins via ribosomes
- protein containing vesicles pinch off from rough ER; migrate to fuse w/golgi membrane
- proteins modified in golgi compartments based off signaling instructions
- proteins packaged w/in vesicle
- secretion via exocytosis at plasma membrane
Nuclear Envelope structure/function
Double lipid bilayer barrier that encloses the jelly-like fluid, the nucleoplasm; contains outer layer (continuous w/rough ER and has ribosomes) and an inner layer (nuclear lamina); nuclear pores
maintains nuclear shape and acts as scaffolding for DNA
Nuclear pores control what goes in and out of nucleus
nucleoli structure/function
1-2 Dark-staining spherical bodies within nucleus per cell
involved in ribosomal RNA (rRNA) synthesis and ribosome subunit assembly; houses DNA
chromatin structure/function
threadlike strands of DNA (and a little RNA) wrapped around histone proteins;
Arranged in fundamental units called nucleosomes
Chemical alterations of histones have an effect on DNA and therefore can
help regulate gene expression!!!!
Phases of the cell cycle
Interphase and growth (mitotic) phase
Interphase
Period from cell formation to cell division; cell carries out routine activities
and prepares for cell division by replicating DNA
nuclear material is in uncondensed chromatin state
three sub-phases: G1, S, G2
G1
first substage of interphase
vigorous growth and metabolism
S (synthetic)
middle sub-stage of interphase
DNA replication
G2 (gap 2)
final sub-stage of interphase
preparation for cell division
M (mitotic) stage
cellular division consisting of mitosis and cytokinesis to create two identical daughter cells
Mitosis
division of nucleus with duplicated DNA distributed to new daughter cells
Prophase, metaphase, anaphase, telophase
prophase
Early:
- chromatin condenses to form sister chromatids
Late:
- nuclear envelope dissolves; microtubules begin to pull chromosomes towards equator and push cell poles further apart
metaphase
chromatids align at the cell equator
anaphase
centrioles pull one part of each sister chromatid to the pole via kinetochore motor proteins
telophase
each set of chromosomes uncoil, nucleoli reappear, and nuclear membranes form
result in two identical cells
cytokinesis
begins during late anaphase and continues through mitosis
actin microfilaments pinch the daughter cells apart
role of cell cycle checkpoints
make sure that cell division is precise and accurate; results in mutations if errors aren’t caught and ensures that cells only divide when necessary
three cell cycle checkpoints
Cell growth checkpoint= end of G1; ensures that cell is big enough and has proper proteins
DNA synthesis checkpoint= during S phase; checks that DNA replicated correctly
Mitosis checkpoint= during M phase; checks that mitosis is complete before cell divides
epithelium definition
sheet of cells that line all body surfaces, body cavities, and tubular organs
function as barriers
epithelium arises from all three embryonic germ layers: _____, ______, and ______.
ectoderm (skin)
endoderm (organ lining)
mesoderm (blood vesssels)
characteristics of epithelium
tightly packed cells w/little to no intercellular substance = uniform strong barrier
avascular (no blood vessels) so nutrients diffuse
capable of regeneration and repair
polarized (two different ends)
apical surface epithelium
exposed to external environment
basal surface of epithelial cell
lies on a supporting connective tissue but separated by a basement membrane made of basal lamina and laminin
basement membrane
layer of collagenous fibers (basal lamina) and laminin separating epithelial cells from connective tissue
simple epithelial cells definition
single layer of cells
four types of simple epithelial cells
simple squamous
simple cuboidal
simple columnar
pseudostratified columnar
simple squamous
cells are very flat –> gases and liquids diffuse easily
line moist internal surfaces
endothelium, mesothelium, or epithelium (no special name)
endothelium
simple squamous cells lining all blood vessels, lymphatics, and the heart
mesothelium
simple squamous epithelium cells lining serous body cavities/tubular abdominal organs
epithelium (as a type of simple squamous cells)
line small tubules in kidneys in the thin loops of nephron
simple cuboidal epithelial cells description and location
width and height of cells are equal
line small ducts
simple columnar epithelial cells description and location
height of cells > width
line GI tract –> have secretory and absorptive capability
pseudostratified columnar epithelial cells
columnar cells; all tough basement membrane but not all reach the lumen (look layered but are NOT)
reproductive and resp. tracts –> move particulate matter
usually have cilia
stratified epithelial cells definition and three types
two or more layers of cells – top layer defines the epithelium
stratified squamous
stratified cuboidal/columnar
transitional
stratified squamous epithelium description and location and types
squamous surface cells, other layers polyhedral
protective!
two types:
- keratinized (dry): surface cells synthesize karatin; ex: skin
- non-keratinized (wet): surface cells are viable; have connective tissue protrusions; found in transition space from keratinized to inside of body; ex: esophagus, inside of mouth
stratified cuboidal/columnar epithelial cells description and location
surface layer is cuboidal or columnar
line large ducts
stratified transitional cells description and location
layered epithelium that changes between cuboidal and columnar depending on state and distention (top layer more puffy when relaxed vs distended)
all cells contact basement membrane
found in urinary tract ONLY
functions of epithelium (7)
protection (skin)
secretion (endocrine glands)
absorption (intestine)
excretion (kidney tubules)
sensation (tastebuds, retina)
transportation (trachea)
reproduction (testes)
