Lecture 1.02 - Cells and Tissues 1

cytology

basic structural and functional units of all living organisms

somatic cells

body cells (muscle or nerve cells)

germ cells

sex cells (sperm and oocytes)

Light Microscopy (LM)

visible light passes through the cells; sample is stained

Transmission Electron Microscopy (TEM)

a beam of electrons passes through thin slice of specimen; 2D image

Scanning Electron Microscopy (SEM)

beam of electrons bounces off surface of cell; 3D image of cell surface

characteristics of living things

organization, metabolism, growth and development, responsiveness, adaptation, regulation, reproduction

cell functional category: covering

protect outer surface of body; ex. epithelial cells of skin

cell functional category: lining

regulate nutrient movement into body tissues; ex. epithelial cells in small intestine

cell functional category: connection (attachment)

form ligaments that attach bone to bone, tendons connecting muscles to bones; ex. collagen fibers from fibroblasts

cell functional category: movement

move skeleton; ex. skeletal muscle cells, cardiac muscle pumping blood in the heart

cell functional category: communication

send information between regions of the brain and spinal cord; ex. neurons

cell functional category: defense

produce antibodies to target antigens or invading cells; ex. lymphocytes

cell functional category: storage

store carbohydrate nutrients as glycogen; ex. hepatocytes, adipocytes storing lipid reserves

cell functional category: reproduction

produce a new individual; ex. sperm cells and oocyte cells, bone marrow stem cells producing new blood cells

inclusions

substances that are being stored inside cells like melanin pigment in skin cells, and also glycogen in liver and skeletal muscle cells

integral proteins

embedded within and extending through the phospholipid bilayer, receptors serve as binding sites for molecules outside the cell, glycoproteins form part of the glycocalyx

peripheral proteins

attached to either internal or external surface of membrane, more soluble type

glycocalyx

functions in communication, cell-cell recognition, and intracellular adhesion

intracellular fluid

cytosol part of cytoplasm

extracellular fluid

interstitial (intercellular) fluid between cells, plasma in blood vessels, lymph in lymphatic vessels

plasma membrane permeability is based on:

molecule size, concentration gradient, ionic charge, lipid solubility, transport (carrier) proteins

glycogen

storage unit molecule of glucose that is stored in the liver and skeletal muscle cells

lipid droplets

accumulations or triglyceride molecules in adipocytes

melanin

pigment in the skin, hair, and eyes that protects the body from the sun’s ultraviolet light

lipofuscin

brown-yellow pigment that is associated with nerve cell bodies; known as aging pigment

rough er

continuous with nuclear envelope; consists of parallel flattened membranous sacs called cisternae; ribosomes are attached to the cytoplasmic side of membranes; produce proteins that are targeted for cell export

smooth er

continuous with rough er but not covered by ribosomes; interconnected branches of tubules; involved with synthesis, transport, and storage of lipis, metabolism of carbohydrates, and detoxification of drugs/alcohol

golgi apparatus

receives and modifies proteins received from the er; sorts and packages materials destined for the plasma membrane or for lysosomes; consists of stacked cisternae

cis-face

receiving region

trans-face

shipping region

endomembrane system

nuclear envelope, endoplasmic reticulum, golgi apparatus, vesicles, lysosomes, plasa membrane

endocytosis

digest material brought into the cell

autophagy

break down substances as part of removal of worn-out or damaged organelles

autolysis

digestion of the cell itself

peroxisomes

convert hydrogen peroxide to water and break down fatty acids

cristae

shelf-like folded inner membrane; increases the available surface area for ATP synthesis

matrix

internal fluid

free ribosomes

float freely in the cytosol; responsible for protein production for use in the cell

bound ribosomes

attached to rough er and outer membrane of nuclear envelope; responsible for producing proteins destined to be incorporated into the plasma membrane, exported from the cell, or housed within lysosomes

microfilaments

7 nm, actin protein, associated with terminal web, participate in muscle contraction, separate cells during cell division

intermediate filaments

8-12 nm in diameter, keratin protein, associated with some cell-cell junctions

microtubules

hollow tubules 25nm in diameter, tubulin protein, radiate from the centrosome and are associated with the mitotic spindle, hold organelles in place, associated with cilia and flagella, not permanent structures in the cell

centriole

made up of nine microtubule triplets arranged in a circle

microtubule organizing center

matrix of the organelle, that supports the growth and elongation of microtubules in nondividing cells

cilia and flagella

projections extending from cell, contain cytoplasm and support microtubules (nine doublets in a circle plus a central pair) enclosed by the plasma membrane

cilia

found in large numbers on apical surfaces of cells that line tracts; ex. respiratory tract use cilia to move mucus

flagella

longer than cilia and usually singular; ex. tail of sperm that propels the cell along

microvilli

thin, short extensions from the plasma membrane, smaller tan cilia with different internal structure and nonmotile, form brush border; ex. lining of the small intestine to increase surface area for absorption of nutrients

axoneme

within cilium that has nine doublets of microtubules peripherally and a central pair of microtubules

basal body

nine triplets of microtubules at the edge of the cell in the cytoplasm, often at the apical margin

nuclear dna

controls cellular activity and stores genetic material

nuclear envelope

a double membrane that separates cytoplasm from nucleoplasm

nuclear pores

openings in the nuclear envelope

nucleoli

made of RNA and make ribosome subunits; can be more than one in the nucleus

mononucleate/uninucleate

single nucleus

anucleate

no nucleus; ex. erythrocytes

binucleate

two nuclei; ex. umbrella cells in bladder

multinucleate

many nuclei; ex. osteoclasts in bone

neutrophils

has nucleus with multiple lobes

genes

nuclear dna organized into discrete units

nucleotides

building blocks of dna molecule

chromatin

dna wrapped around histone proteins

chromosomes

condensed structure of dna when a cell begins to divide

mitotic (m) phase

when cell is dividing

interphase

cell carries out normal metabolic activities, rests, or prepares for a future cell division

mitosis

cell division process relating to most cells in the body

meiosis

cell division process that relates to sex cells

four sub-phases of the mitotic phase

prophase, metaphase, anaphase, and telophase

cytokinesis

division of cytoplasm at the end of mitosis

apoptosis

normal programmed cell death

necrosis

accidental cell death by harmful agents or mechanical damage

g0 phase

state of arrested development, nondividing cells like neurons remain

g1 phase

first growth or gap phase in which cells grow and produce new organelles and proteins; end of phase centrioles begin replicating

s phase

synthesis phase during which each dna molecule is replicated

g2 phase

second growth or gap phase in which centriole replication is completed and organelles continue to be synthesized

equatorial plate

where replicated chromosomes line up during metaphase

cleavage furrow

formed through contractile ring of actin protein filaments

cytokinesis

cleavage furrow deepens further as cytoplasm