Exam 2 Flashcards
Parts of the cell
Plasma membrane, cytoplasm (cytosol and organelles), and nucleus
Characteristics of plasma membrane
- Composed of phospholipid bilayer 2. Flexible 3. Selective permeability
2 arrangement of membrane proteins
Integral proteins (including transmembrane proteins) and peripheral proteins
Functions of membrane proteins
Ion channels, transporters (carriers), receptors (binds to ligands), linkers, and cell identity markers (MHC proteins)
True/False: Phospholipids are in constant motion
True
True/False: Plasma membrane has selective permeable.
True
What alters permeability?
Ion channels and transporters
What is permeable to plasma membrane?
Small, uncharged, nonpolar molecules (ex: oxygen, CO2)
What is weakly permeable to the plasma membranes.
Small, uncharged, polar molecules (ex: water)
What is impermeable to the plasma membranes?
Ions and large molecules
Gradients across the membrane is dependent on __________.
Selective permeability
Two types of gradients across the membrane
Concentration and electrical gradient
Two types of transport across the membrane
Passive and active transport
What are the mechanisms of passive transport?
Simple diffusion, facilitating diffusion, and osmosis
What are the mechanisms of active transport?
Transport via transport proteins and transport via vesicles
Two forms of active transport
Primary and secondary active transport
Transport via vesicles
Large molecules or large amount of a substance can move across membrane,”packaged” within the vesicle
Endocytosis includes:
Receptor-mediated endocytosis, phagocytosis, and pinocytosis (bulk-phase endocytosis)
Kinds of cytoskeleton
Microfilaments, intermediate filaments and microtubules
What does reticulum mean?
Network
Two types of ER
Rough and smooth ER
What is the function of vesicles that pinch off from mature cisternae at other end of Golgi complex?
Either store proteins (lysosomes) or deliver proteins to plasma membrane for insertion in membrane for insertion in membrane or exocytosis
How many chromosomes does a human somatic (body cell) have?
46
Two stages of gene expression
Transcription and translation
Where does transcription occur?
In the nucleus
3 types of RNA
mRNA, rRNA, tRNA
Where does the RNA polymerase attaches to start transcription?
A DNA molecule at a promoter sequence
Where does the process of transcription ends?
At terminator sequence in DNA
Where does translation occurs?
In cytoplasm, often on rough ER
Describe the ribosomal structure.
- Small subunit has binding site for mRNA 2. Large subunit has two binding sites for tRNA
Two binding sites in the large subunit for tRNA
P site and A site
What is always the first amino acid in translation?
Met
What is the process for somatic (soma= body) cell division?
Mitosis; one diploid parent (2N) parent cell –> two 2N daughter cells
What is the process for reproductive cell division?
Meiosis; one 2N parent cell –> 4 haploid (1N) cells (gametes)
2 phases of somatic cell cycle
Interphase and mitotic phase
3 phases of interphase
G1, S, and G2 phases
Mitotic phase includes?
Mitosis and cytokinesis
4 stages of mitosis
Prophase, metaphase, anaphase, and telophase
Tissue structure and function depend on:
Cell types Types of connections between cells Nature of extracellular materials
Four types of tissues in human body
Epithelial Connective Muscular Nervous
Five types of cell junctions
Tight and adherens junction desmosome hemidesmosome gap junction
Basic structural and functional unit of living organisms
Cell
Allows for movement of membrane during growth, maintenance, and repair; plasma membrane and its components can move
Membrane fluidity
Requires no energy input from the cell; a substance moves down its concentration or electrical gradient
Passive transport
Requires energy input from cell; a substances drive against its concentration or electrical gradient
Active transport
Molecules move from an area of high concentration to area of low concentration until equilibrium is reached; small, uncharged molecules (polar or nonpolar) diffuse across membrane, ex: O2, CO2, H2O
Simple diffusion
Large, charged, or highly polar molecules require assistance to move across membrane: uses ion channels and transporters proteins
Facilitated diffusion
Diffusion of solvent (WATER) across a selectively permeable membrane; moves from area of higher water conc. to area of lower water conc.; moves from area of lower solute conc. to area of higher solute conc.
Osmosis
Pressure driving water from area of low to area of high solute concentration
Osmotic pressure
Ability of a solution to change the volume of a cell by osmosis; relative concentration of solution of the ECF and ICF
Toxicity
ECF and ICF have same concentration of solutes; no net movement of water and cell does not change volume
Isotonic solution
ECF had less solute than ICF; water enters cell faster than it leaves; cells swells and my burst (lyse)
Hypotonic solution
ECF has more solutes than ICF; water leaves cell faster than it enters; cell shrinks (crenation)
Hypertonic solution
By expending energy, cells can move molecules against their concentration or electrical gradient
Active transport
Energy derived from ATP and used to change shape of transporter protein; ex: sodium potassium pump
Primary active transport
Energy derived from an ion concentration gradient (usually Na+) and energy is used to change shape of transporter protein; simultaneously moves Na+ and another molecule
Secondary active transport
Small sac formed by budding off from an existing membrane
Vesicle
Movement of substances into cell via vesicles
Endocytosis
Cell takes in select molecules (ligands); molecule binds to receptor protein on plasma membrane; transports to individual molecules and highly specific
Receptor-mediated endocytosis
Cell engulfs large solid particles; molecules bind to receptor proteins, transports individual molecules of larger particles and highly specific
Phagocytosis
Cell engulfs fluid (and dissolved solute); no receptor proteins are involved and transports many molecules at once (not specific)
Pinocytosis (bulk-phase endocytosis)
Movement of substances out of cell via vesicles; vesicle formed inside cell and fuses with plasma membrane to release contents
Exocytosis
Movement of substances across a cell via vesicles; linking endocytosis at one cell surface and exocytosis at other surface
Transcytosis
Network of protein filaments extending throughout cytosol
Cytoskeleton
Small in size; composed of actin and provide structural support for cell; involved in cell movement
Microfilaments
Medium size; composed of several different proteins and provide structural support for cell; holds nucleus and other organelles in place
Intermediate filaments
Large size; composed of tubulin molecules arranged in hollow tubes; determines shape of cell and involved in movement of organelles, chromosomes, cilia and flagella
Microtubules
Composed of microtubules; project from surface of some cells; unreliable and short and involved in movement of extracellular fluid
Cilia
Composed of microtubules; project from surface of some cells; singular and long and propels cell from fluid
Flagella
Located near nucleus; composed of two centrioles and is the organization cent for mitosis spindle
Centrosome
Composed of two protein subunits; contain rRNA; most attached to endoplasmic reticulum and function is protein synthesis
Ribosome
Network of membranes extending throughout the cell, forming flattened sacs or tubules
Endoplasmic reticulum (ER)
Folded into series of flattened sacs; ribosomes attached to outer surface and proteins synthesize by ribosomes are modified inside sacs formed by ER
Rough ER
Lack of ribosomes; site of synthesis of fatty acids and steroids
Smooth ER
Transports proteins throughout cell or to cell surface for secretion; Series of flattened membranous sacs (cisternae/cisterna = cavities); Looks like a cup
Golgi complex
carry proteins from rough ER to Golgi complex, creating the young cisternae at one end of Golgi complex
Transport vesicles
Membrane-bound organelle; “Powerhouse” of the cell; Site of most of ATP production via aerobic respiration
Mitochondria
Control center of the cell; A double membrane composed of two phospholipid bilayers; Contains nucleolus/nucleoli; Contains genetic information for cell structure and function
Nucleus
Allow substances to cross the nuclear envelope (passive or active transport)
Nuclear pores
Sites of ribosome formation
Nucleolus/nucleoli
A section of a DNA molecule that codes for a particular protein; composed of a sequence of base triplets
Gene
A sequence of three nucleotides; codes for a particular amino acid in the protein
Base triplets
DNA uses a template to synthesize a protein
Gene expression
Information encoded in DNA copied to mRNA; Base triplets of DNA transcribed as a codon in mRNA
Transcription
Information encoded in RNA used by ribosome to produce protein; Codons of mRNA for amino acids in protein
Translation
Gametes and precursors
Germ cells
Period of metabolic activity and cell growth; Chromosomes and organelles have duplicate Chromosomes in diffuse form (chromatin) Nuclear envelope intact
Interphase
Period of cell division
Mitotic phase
Metabolic activity Replication of organelles Centrosome replication begins
G1 phase (G = growth)
Replication of DNA Double helix partially uncoils Each strand serves as a template for the synthesis of a new complementary strand
S phase (S=synthesis)
Metabolic activity Cell growth Centrosome replication is completed
G2 phase
Division of nucleus (including chromosomes) between daughter cells; a continuous process
Mitosis
Division of cytoplasm (including organelles) between daughter cells
Cytokinesis
Nuclear envelope disintegrates Chromosomes in condensed form (chromatid pairs) Homologous chromatids joined by centromere Centrosome begin to produce a mitosis spindle composed of microtubules
Prophase
Chromatid pairs line up along equator of the cell Centromeres aligned at the center of the mitotic spindle
Metaphase
Centromeres split Members of chromatid pairs (chromosomes)move toward opposite poles of the cell Microtubules of mitotic spindle pull on centromeres of the chromosomes
Anaphase
Chromosomes reach opposite poles of the cell New nuclear envelopes form Cytokinesis involves formation of cleavage furrow
Telophase
Groups of cells and associated extra cellular materials that work together to perform a particular function
Tissues
Cells within a tissue are usually joined together at their plasma membrane
Cell junctions
Trans-membrane proteins tightly link cells together; Tissues are relatively impermeable
Tight junction
Trans-membrane proteins link cells together; Trans-membrane proteins anchored to microfilaments of cytoskeleton; Tissues resist separation during movement
Adherens junction
Trans-membrane proteins link cells together; Trans-membrane proteins anchored to intermediate filaments of cytoskeleton; Tissues resist separation during movement
Desmosome
Similar structure to desmosome; Links cells to basement membrane, rather than to other cells
Hemidesmosome
Plasma membrane of adjacent cells not touching; Trans-membrane proteins form tubes between cells; Allows for communication between cells
Gap junction
Cover body surfaces and line body cavities Form functional regions of glands Cells arranged in continuous sheets
Epithelial tissue
Faces body surface or internal body cavity
Apical surface
Adheres to basement membrane
Basal surface
Consists of basal lamina and reticular lamina
Basement membrane
Secreted by overlying epithelial cells
Basal lamina
Secreted by underlying connective tissue
Reticular lamina
Functions of epithelial tissue
Form selective barriers to passage of susbtances into and out of body
absorption of nutrients
excretion of waste products
secretion of hormones, digestive juices, etc
form protective surfaces against external environment
type of epithelial cell that is flattened
squamous epithelium
type of epithelial cell that are cubed-shaped or hexagonal
cuboidal epithelium
type of epithelial cell that are taller than they are wide
columnar epithelium
type of epithelial cell that can change shape as tissue stretches
transitional epithelium
type of epithelial cell that is composed of a single cell layer
simple epithelia
type of epithelial cell that is composed of multiple cell layers
stratified epithelia
type of epithelial cell that is composed of a single cell layer, but individual cells may not extend from basal to apical surface
pesudo-stratified epithelia
tissues within a gland that secrete substances
glandular epithelia
ductless glands that secrete products (hormones) into interstitial fluid (then blood stream)
endocrine glands
glands with ducts that secrete products (mucus, sweat, digestive enzymes, etc.) into ducts that empty to body surface (e.g. sweat gland) or lumen of organ or tract (e.g salivary gland)
exocrine gland
3 classifications of exocrine glands
merocrine
apocrine
hoocrine
secrete products via secretory vesicles and exocytosis
merocrine glands
mammary glands; they secrete products via pinching off of apical surface of cell
apocrine glands
sebaceous (oil) glands; secrete products via rupture of cell
holocrine glands
connective tissue functions
- binds body structure together
- provides support
- transports nutrients and wastes
- stores energy
- protects body via immune response
secreted by fibroblasts
connective tissue fibers
type of protein fiber that are thick, straigh, and un-branched; also strong and flexible
collagen fibers
type of protein fiber that are thin and branching, strong and flexible
reticular fibers
type of protein fiber that are thin and branching, and elastic (returns to original size and shape after stretching)
elasic fibers
type of cartilage that found at joints and ends of long bones; reduces friction between articulating bones
hyaline cartilage
type of cartilage that frames intervertebral disks and prevents bone-to-bone contact
fibrocartilage
type of cartilage found in external ear and provides structural support
elastic cartilage
flat sheets of tissue that cover or line part of the body
tissue membranes
type of membrane that line body cavities that open to external environment;
forms barrier to pathogens and secretes mucus that prevents dessication
mucous membrane
type of membrane that lines internal body cavities and covers organs within internal body cavities
serous membrane
type of membrane that consists of epidermis and dermis
cutaneous membrane
type of membrane that lines cavities of mvable joints and secretes synovial fluid
synovial membrane
layer of the epidermis that has one layer of cuboidal or columnar keratinocytes; contains many stem cells that give rise to new keratinocyes
stratum basale
layer of the epidermis that has 8-10 layers of keratinocytes
living cells and keratinocyes begin producing keratin at this stage
stratum spinosum
layer of the epidermis with 3-5 layers of flattened keratinocytes, and where the younger keratinocyes produce lamellar granules consisting of hydrophobic keratohyalin that causes dehydration of cell and waterproofs skin
stratum granulosum
slayer of the epidermis with 3 to 5 layers of dead, flattened keratinocytes and provides extra protection for thick skin
stratum lucidum
layer of the epidermis that has 25-30 layers of dead, flattened keratinocytes; superficial layers are shed and replaced by new layers from below
stratum corneum
