Lecture 03 - Vocabulary

Robert Hooke (1665)

Inventor of microscopes (light) to study biological materials

Schwann (1839)

proposed all animals consist of cells

when cell forms part of a larger organism → has individual life of its own

Schleiden

concluded all plants are made of cells

Prokaryote

No nucleus

Few/no membrane bound organelles

Small, 1-10 µm

Domain Eubacteria

Domain Archaea

Circular DNA

Eukaryotic Organisms

DNA linear chromosomes

Larger (10-100 µm)

Domain Eukarya

Plants, Animals, Fungi, Protists: Algae, Protozoa are all…

Eukaryotes

Flagella

Composed of protein (flagellin)

Embedded in CW structure

Enable movement

Gram positive

Thick cell wall of peptidoglycan

Purple when stained

Gram negative bacteria

Thin CW of peptidoglycan

Outer membrane (additional boundary) has LPS

Lipopolysaccharides

Large molecule made of lipid and a carbohydrate joined by a covalent bond

Chromsomes

Coiled around proteins to form → nucleosomes

Thread-like structure in nucleus carrying genetic information

Histones

Small (positively charged) class of proteins that bind DNA → forms nucleosomes

Cell fractionation

techqnieu that divides cells into fractions contains a single cell component

Compartments are for

Organizing specific biological functions: protein synthesis, energy metabolism, digestion

Cytoplasm

Space between nucleus and plasma membrane

Cytosol

Between organelles, mostly water with dissolved proteins, amino acids, nucleic acids, sugars, polysaccharides

Aqueous solution (water) with ions + organic molecules

Membrane bound organelles

An organelle within a cell surrounded by a phospholipid bilayer membrane & filled with aqueous solution

Nucleus

DNA’s control center

Has most of cells DNA

5 µm in diameter

Nuclear envelope

Surrounds nucleus

two phospholipid bilayers with fluid filled space in between them

Nuclear lamina

Network of fibrous proteins

Anchors chromosomes

Provides nucleus strength

Nuclear pore complex

100 µm in diameter, a supramolecular system

50+ proteins pass = open the pore, selective only specific things enter/leave

Controls exchange of material between nucleus + cytoplasm

Chromatin

Complex of DNA hereditary material + protein

Nucleolus

rRNA synthesis site & assembly of ribosomal units

Along edge of chromosomes

Nucleolar organizers

Sections on chromosomes where nucleolus forms

has genes for rRNA

Ribosome

Free, protein synthesis

Protein + rRNA

Ribosomes can be attached to

Rough ER

Nuceleus

Molecular weight of Prokaryotic Ribosome (70S)

2.5 MDa

Molecular weight of Eukaryotic Ribosome (80S)

4.2 MDa

Free Ribosome

Not membrane bound organelle

Endomembrane system

In eukaryotes

Collection of interrelated internal membranous acts divide a cell into functional + structural components

Name the components of endomembrane system

Nuclear envelope

Endoplasmic Reticulum

Golgi Complex

Lysosomes

Vesicles

Plasma membrane

Vesicles

small, membrane bound compartment transfers substances between parts of the E.S.

Endoplasmic reticulum

Labyrinth of membranous tubes and sacs

Lots of luminal space inside with enzymes

Smooth ER

synthesis of lipids

carbohydrate metabolism (liver)

detoxification (adding OH group)

Store Ca2+

Rough ER

Synthesis site of secretory proteins, membrane proteins, and proteins of endomembrane organelles

Products shipped → Golgi by vesicles

Detoxification of smooth ER can…

make something hydrophilic → moves it out of the membrane → cytosol (effect of adding a OH group

Golgi body

Shipping/Receiving Center
Modification/Distribution of proteins, routes proteins

Lysosome

Membrane bound organelle with enzymes for digestion of complex molecules

Lipase

Breaks down ester linakges

Phospholipids → FA + glycerol

Carbohydrases

Attacks glycosidic linkages → simple sugars

Proteases

Digests peptide linkages

Nucleases

cuts phosphodiester bonds that link DNA and RNA

vacuole

fluid-filled space enclosed by a membrane in cytoplasm

peroxisomes

arise from other peroxisomes

abundant in plants

oxidation of lipids & FA (add O2 → FA)

Oxidases

transfer H+ from substrate → (at the expense of O2) to form peroxide

Catalase

Can attack a toxin using peroxide, catalyzes removal of peroxide → H2O

Cellular respiration

Sugars → broken down into

CO2 + H2O + ATP

Goal is to regenerate ATP

Mitochondria structure

two phospholipid bilayers

two membranes

outer membrane/inner(highly folded)

fluid filled inter membrane space between, matrix is filled

cristae

fold that expands the surface area of the inner mitochondrial membrane.

matrix

innermost compartment of mitochondria

chloroplasts

site of photosynthesis

conver solar energy → chemical energy

Photosynthesis reaction

CO2 + H2O → sugars

requires energy

Stroma

fluid interior

houses enzymes to fuel carbohydrates production

has DNA and ribosomes

Thylakoids

A flattened, closed sac within the stroma of a chloroplast.

Grana

Stacks of thylakoid discs

Endosymbiotic theory

Origin of mitochondria & chloroplasts are from bacteria

Gram negative bacteria → taken into an endoscope, bacteria had home, food and eukaryote produced lots of ATP

Bacteria had required genes to produce proteins

Ubiquitin

short-lived proteins are marked for breakdown by enzymes that attach a “doom tag” - present in most eukaryotes

Cytoskeleton

Cytosol network of fibrous proteins

Proteasome

Non-membrame, multimeric (made of smaller subunits), has 100+ polypeptides

Degrade proteins in nucleus, cytosol, and membrane

In eukaryotic cells, degrades ubiquitinylated proteins.

Three Types of Elements in Cytoskeleton

Framework, Support, Movement: by motor proteins, kinesis, dyeing, myosin

Domain

certain area for folding to perform a function

Dyenin

Walk along microtubule, dragging payload behind, carries cargo → cell periphery → inward

Myosin

walks along microfilaments/around

Microtubules

largest

globular proteins (round)

alpha and beta tubulin

Microfilaments

smallest

two actin molecules - hooked together tightly, and coiled

solid rods

has ± end - is polar

± end

kinesin/dyenin use for direction

Intermediate filaments

keratin subunits

not dynamic, does not return

help determine cell shape

determine locations of membrane-bound organelles

provides tracks for intracellular transport

move/separate chromosomes during cell division

determine growth patterns CWs

microtubule

direct changes in cell shape, direction of cell movement

determine location of membrane-bd organelles in plant cells

form cross-links between other cytoskeletal filaments

provides tracks, interact w/ myosin → generate forces

microfilament function

found in animal cells

support nuclear envelope

determine cell shape

form durable attachments between cells in tissues

intermediate filament function

determine cell shape

determine location of membrane bound organelles in animal cells

provide tracks for intracellular transport

move/separate chromosomes during division

determine plant cell wall growth patterns

microtubule

actin

protein involved in microfilament force production for muscle contraction

flagellum

hair like structures projecting from plasma membrane (long)

in prokaryotes/eukaryotes

responsible for movement

cilia

motile structure, extends form cell surface → moves a cell through fluid, or fluid over a cell

9 + 2 complex

9 outer microtubule doublets + 2 central microtubules

present in basal bod of a flagellum

centrosome

a membraneless organelle, at center of cell, which microtubules radiate outward

centriole

in animal cells: 2 short, barrel-shaped structures from microtubules

organizes microtubules + forms centrosomes (organize networks), forms basal bodies for cilia/flagella

peptidoglycan

polymeric substance derived from polysaccharide backbone tie together by polypeptides → primary structural molecule of bacterial CW

Cell wall

Rigid structure outside plasma membrane

Found in Plants, Fungi, Bacteria, and Most Algae

Prevent excess water uptake, serve as protection, maintain shape

Extracellular Matrix

In animals, web of glycoproteins, EC proteins, polysaccharides associated with outer face of PM

Support, adhesion, cell communication, regulation of cellular function

Tight junction

region of tight connection between membranes of adjacent cells

prevents passage of substance

gap junction

open direct channels allow ions and small molecule passage directly form one cell → another