concept 2b Flashcards
cell theory
- all living things are composed of cells
- the cell is the basic functional unit of life
- cells arise only from preexisting cells
- cells carry genetic information in the form of DNA. this genetic material is passed on from patron to daughter cell
eukaryotic cells
contain a true nucleus enclosed in a membrane
organisms can be unicellular or multicellular
contain many organelles in the cells
reproduce by mitosis allowing the formation of 2 identical daughter cells
prokaryotic cells
do not contain a nucleus
nucleus
control center of the cells
contains genetic material encoded in DNA, organized into chromosomes
surrounded by the nuclear membrane (envelope)
nuclear pores
in the nuclear membrane
allow for selective 2-way exchange of material b/w the cytoplasm and the nucleus
nucleolus
subsection of the nucleus
synthesizes rRNA
about 25% of the volume of the entire nucleus and can often be identified as a darker spot in the nucleus
mitochondria
power plants of the cell
important in metabolic functions
contains 2 membranes, inner and outer
contain some of their own genes and replicate independently of nucleus via binary fission
capable of killing cell by release of enzymes from ETC to kickstart apoptosis
mitochondrial matrix
space inside the inner membrane
pumping of protons from the matrix to the inter membrane space (out of the matrix) establishes the proton-motive force, protons then flow through ATP synthase to generate ATP during oxidative phosphorylation
lysosomes
membrane-bound organelle
contain hydrolytic enzymes that are capable of breaking down many different substrates
autolysis
process of release of lysosome enzymes
results in apoptosis
release of enzymes directly lead to degradation of cellular components
endoplasmic reticulum
interconnected membranes that are continuous with the nuclear envelope
folded into numbers invaginations creating complex structures w/ a central lumen
2 varieties: smooth and rough
rough ER
studded with ribosomes
site of protein translation that are destined for secretion directly into lumen
smooth ER
lacks ribosomes
utilized for lipid synthesis and detoxification of certain drugs and poisons
transports proteins from the RER to the Golgi apparatus
Golgi apparatus
consists of stacked membrane-bound sacs
modifies, sorts, and repackages, and transferred to correct cellular location in vesicles
materials are transferred from the ER to the Golgi and vesicles
peroxisomes
contain hydrogen peroxide
primary function is the breakdown of long chain fatty acids via beta-oxidation
participate in the synthesis of phospholipids and contain some of the enzymes involved in pentose phosphate pathway
cytoskeleton
provides structure to the cell and help it to maintain its shape
provides a pathway for the transport of material around the cell
3 components: microfilaments, microtubules, and intermediate filaments
microfilaments
made up of polymerized rods of actin
actin filaments are organized in bundles and networks that provide protection for the cell
role in cytokinesis, division of materials b/w daughter cells, during mitosis the cleavage furrow is formed from microfilaments
microtubules
hollow polymers of tubular proteins
provide primary pathway along witch motor proteins like chines and dyne carry vesicles
cilia and flagella are motile structures composed of microtubules
cilia
projections from a cell that are primarily involved in moment of materials along the surface of the cell
one projection
made up of microtubules
flagella
structures involved in movement of the cell itself
multiple small, hairlike projections
made up of microtubules
centrioles
found in centrosome
organizing centers for microtubules
structured as 9 triplets of microtubules with hollow center
migrate to opposite poles of dividing cell in mitosis and microtubules originate from these and attach to chromosomes at the kinetochores
intermediate filaments
diverse group of filamentous proteins, including keratin and desmin
involved in cell-cell adhesion or maintenance of the overall integrity of the cytoskeleton
able to withstand a lot of tension making the cell structure more rigid
help to anchor other organelles
tissue types
epithelial tissue
connective tissue
muscle tissue
nervous tissue
epithelial tissue
cover the body and line its cavities
means for protection against pathogen invasion and desiccation
involved in absorption, secretion, and sensation
tightly joined to each other and to an underlying layer of connective tissue
tissues are diverse and serve numerous functions depending on the identity of the organ
often polarized, one side faces a lumen or outside world and other interacts w/ blood vessels and structural cells
parenchyma
the functional parts of the organ
in most organs this constitutes as epithelial cells
classes of epithelial cells by # of layers
simple epithelia: single layer of cells
stratified epithelia: multiple layers of cells
pseudo-stratified epithelia: appear to have multiple layers due to differences in cell height but only have one layer