Cell Structure and Function: Organelles, Protein Synthesis, and Energy Production

Cells

the basic structure and functional units of every organism

Prokaryotic cells

Domains in bacteria and archaea; DNA is in nucleoid region; generally smaller in size than eukaryotes

Eukaryotic cells

Cells that contain membrane-bound organelles and DNA in the nucleus

Organelles

membrane bound structures found in eukaryotic cells

Endomembrane organelles

Includes nuclear envelope, endoplasmic reticulum, Golgi complex, lysosomes, vesicles/vacuoles, and plasma membranes

Energy organelles

Includes mitochondria and chloroplasts

Compartmentalization

Allows for different metabolic reactions to occur in different locations, increases surface area for reactions, and prevents interfering reactions from occurring in the same location

Unique Cell Components in Plants

Chloroplasts, central vacuole, cell wall, plasmodesmata

Unique Cell Components in Animals

Lacks chloroplasts, central vacuole, cell wall, and plasmodesmata

Nucleus

Contains chromosomes (genetic information), enclosed by nuclear envelope, double membrane, has pores that regulate entry and exit of materials from cell

Nucleolus

Dense region of the nucleus where ribosomal RNA (rRNA) is synthesized

Ribosomes

Translate messages found on mRNA into primary structure of polypeptides

Transcription

The process of DNA being transcribed by RNA polymerase into messenger RNA (mRNA)

Translation

The process where ribosomes decode the information in mRNA and form continuous chains of amino acids, thus forming a protein

Monomers of Proteins

Amino acids, which contain a carboxyl and amino group

Structural Levels of a Protein

Primary structure, secondary structure, tertiary structure, and quaternary structure

DNA

Deoxyribose, double stranded with anti-parallel connections, contains thymine

RNA

Ribose nucleic acid, single strand, contains uracil

Free Ribosomes

Ribosomes found in the cytosol; Proteins produced here generally function only within the cytosol (I.e. enzymes).

Bound Ribosomes

Ribosomes that are attached to the endoplasmic reticulum or nuclear envelope; Proteins produced here can be secreted from the cell.

Endoplasmic Reticulum

A network of membranous sacs and tubes; Functions: Synthesized membranes, Compartmentalize the cell to keep proteins formed in the ER separate from those free ribosomes.

Rough ER

Type of endoplasmic reticulum that contains ribosomes bound to the ER membrane.

Smooth ER

Type of endoplasmic reticulum that contains no ribosomes; Synthesizes lipids, metabolizes carbs, and detoxifies cell.

Golgi Complex

Contains flattened membranous sacs called cisternae; Functions: Receives transport vesicles with materials from ER, Modifies the materials, Sorts the materials, Add molecular tags, Packages materials into new transport vesicles that exit the membrane via exocytosis.

Cisternae

Separate sacs in the Golgi complex that are not connected.

Lysosomes

Membranous sac with hydrolytic enzymes; Function: Hydrolyzes macromolecules in animal cells.

Autophagy

Process by which lysosomes recycle their own cell's organic materials, allowing the cell to renew itself.

Peroxisomes

Similar to lysosomes; Membrane bound metabolic compartment that catalyze reactions producing H2O2 (hydrogen peroxide) and then break it down to water.

Vacuoles

Large vesicles that stem from the ER and Golgi; Selective in transport.

Food Vacuole

Formed via phagocytosis (cell eating) and then digested by lysosomes.

Contractile Vacuole

Maintains water levels in the cell.

Central Vacuole

Found in plants; Contains inorganic ions and water; Important for turgor pressure.

Albumin

An important protein in humans that functions primarily to regulate oncotic pressure of blood, important for the regulation of fluids in vessels of the body and tissue repair.

Hepatitis C

A virus that attacks the liver and can cause liver disease, linked to a reduction in albumin levels.

Rough Endoplasmic Reticulum

Organelle in liver cells most likely affected by hepatitis C, responsible for holding ribosomes that create proteins.

Insulin

A hormone synthesized by pancreatic cells in the endoplasmic reticulum; Patients with type 1 diabetes cannot produce insulin.

Insulin Production

Insulin would be produced after ribosomes attach to the rough endoplasmic reticulum and get processed as insulin, then sent to the golgi body in order to sort and package the insulin and ship it inside of vesicles to the plasma membrane via exocytosis.

Endosymbiont Theory

The theory that explains the similarities mitochondria and chloroplasts have to a prokaryote.

Prokaryotic Cell

A cell that became an endosymbiont (cell that lives in another cell) after being engulfed by an early eukaryotic cell.

Evidence of Endosymbiont Theory

Double membrane, ribosomes, circular DNA, capable of function on their own.

Mitochondria

Site of cellular respiration.

Outer Membrane of Mitochondria

Smooth.

Inner Membrane of Mitochondria

Has folds called cristae.

Intermembrane Space

Space between inner and outer membrane of mitochondria.

Mitochondrial Matrix

Enclosed by inner membrane; location for the Krebs cycle; contains enzymes that catalyze cellular respiration and produce ATP, mitochondrial DNA, and ribosomes.

Mitochondria and Metabolic Activity

The number of mitochondria in a cell correlates with metabolic activity; cells with high metabolic activity have more mitochondria.

Chloroplast

Specialized organelles in photosynthetic organisms; site of photosynthesis.

Chlorophyll

The green pigment contained in chloroplasts.

Thylakoids

Membranous sacs inside chloroplasts that can organize into stacks called grana; light dependent reactions occur in grana.

Stroma

Location for the Calvin cycle in chloroplasts; contains chloroplast DNA, ribosomes, and enzymes.

Cytoskeleton

A network of fibers throughout the cytoplasm that gives structural support (especially for animal cells) and mechanical movement.

Functions of Cytoskeleton

Anchor organelles, allow for movement of vesicles and organelles and/or whole cell; movement occurs when the cytoskeleton interacts with motor proteins.

Microtubules

Grow from tubulin; assist in centrosome assembly; serve as structural support like train tracks for the movement of organelles interacting with motor proteins.

Functions of Microtubules

Assist in the separation of chromosomes during cell division; cell motility like cilia and flagella.

Microfilaments

Thin solid rods made of the protein actin.

Functions of Microfilaments

Maintain cell shape, bear tension, assist in muscle contraction and cell motility; actin works with myosin to cause contraction.

Intermediate Filaments

Fibrous proteins made up of varying subunits; permanent structural elements of the cell.

Functions of Intermediate Filaments

Maintain cell shape, anchor nucleus and organelles, form nuclear lamina, line nuclear envelope.