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005v2 Tour of the Cell
Beavers Bio 6
1. NOTICE
2. A TOUR OF THE CELL
A. All organisms are made of cells. A cell is the simplest collection of matter
that can live.
3. CELL
A. CELL: The simplest collection of matter that can live. All organisms are
made of cells; some exist as single-celled organisms. More complex
organisms, including plants and animals, are multicellular. Cells are an
organism’s basic units of structure and function.
4. 1997 IMMUNODEFICIENT MOUSE AND EAR
5. 2014 MADE TO ORDER ORGANS
6. SEEING CELLS
A. Robert Hooke, English inventor and scientist, reported in 1665 his findings
from viewing an “exceeding thin…piece of cork”. In 1670’s, Antoni van
Leeuwenhoek (1632-1723) described protists as “animalcules”.
B. The discovery and early study of cells progressed with the invention of
microscopes in 1590 and their refinement during the 1600’s.
7. MICROSCOPY- how do we study cells
A. Light Microscope (LM): An optical instrument with lenses that refract (bend)
visible light to magnify images of specimens.
8. MICROSCOPY
A. Organelle: (previously defined) any of several membrane-enclosed
structures with specialized functions, suspended in the cytosol of eukaryotic
cells. Most light microscopes could not resolve the ultrastructure of the cell.
9. MICROSCOPY
A. Electron Microscope (EM): A microscope that uses magnets to focus an
electron beam on or through a specimen, resulting in resolving power a
thousand fold greater than that of a light microscope.
10.
MICROSCOPY
A. Scanning Electron Microscope (SEM): A microscope that uses an electron
beam to scan the surface of a sample to study details of its topography.
B. Transmission Electron Microscope (TEM): A microscope that passes an
electron beam through very thin sections and is primarily used to study the
internal ultrastructure of cells.
11.
MICROSCOPY
A. SEM: SURFACE OF THE CELL OF A RABBIT TRACHEA (windpipe) COVERED
WITH CILIA. BEATING OF THE CILIA HELPS TO REMOVE INHALED DEBRIS.
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TEM: THIS IS A SECTION CUT THROUGH THE SAME CELLS, REVEALING ITS
ULTRASTRUCTURE (cellular anatomy).
12.
SEM – ANTHER
13.
CELL FRACTIONATION
A. Cell fractionation: The disruption of a cell and separation of its parts by
centrifugation.
14.
CELLS – TWO TYPES PROKARYOTIC and EUKARYOTIC
A. Cytosol (inside all cells): The semi-fluid, jellylike substance in which subcellular components are suspended.
B. Cells: The basic structural and functional unit of every organism is one of
two types of cells: prokaryotic or eukaryotic.
C. PRO MEANS NO.
D. EU MEANS TRUE.
15.
PROKARYOTIC CELLS
A. Prokaryotic cell: A type of cell lacking a membrane-enclosed nucleus and
membrane-enclosed organelles. Organisms with prokaryotic cells, (bacteria
and archaea) are called prokaryotes.
16.
EUKARYOTIC CELL
A. Eukaryotic cell: A type of cell with a membrane-enclosed nucleus and
membrane-enclosed organelles. Organisms with eukaryotic cells (protists,
plants, fungi, and animals) are called eukaryotes.
17.
A.
B.
C.
D.
E.
F.
PROKARYOTIC CELLS
Main difference between prokaryotic and eukaryotic? Location of DNA.
A typical rod-shaped bacterium
A thin section through the bacterium Bacillus coagulans (TEM)
Eu = true
Pro = before
Karyon = “kernel” or nucleus.
A.
B.
C.
D.
E.
F.
G.
PROKARYOTIC CELL
Nucleoid:
Fimbriae:
Ribosomes:
Plasma Membrane:
Cell Wall:
Capsule:
Flagella
18.
19.
PROKARYOTES
20.
CELL: BOUNDARY AND INTERIOR
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A. Plasma Membrane: The membrane at the boundary of every cell that acts as
a selective barrier, regulating the cell’s chemical composition.
B. Cytoplasm: The contents of the cell, exclusive of the nucleus and bounded
by the plasma membrane.
21.
SIZE MATTERS
A. Increasing surface area but not volume…larger organisms have MORE cells –
not larger ones.
22.
EUKARYOTIC CELL
A. Plasma membrane AND the membrane of organelles consist of a double
layer (bilayer) of phospholipids with various proteins attached or embedded
in it.
B. Interior of membrane phospholipids are hydrophobic.
C. Exterior of membrane phospholipids are hydrophilic.
23.
A.
B.
C.
D.
E.
F.
G.
H.
I.
24.
25.
A.
B.
C.
D.
E.
F.
G.
REMEMBER THE PHOSPHOLIPID
Why does membrane work?
Phospholipid has a hydrophilic head.
Phospholipid has a hydrophobic tail.
The bilayer of phospholipids is the perfect design.
A eukaryotic cell has an extensive and elaborately arranged internal
membrane, which divides the cell into the organelles we have already
described.
What is the importance of division? The different compartments allow
specific metabolic functions, or unique and different chemical functions to go
on simultaneously without interference.
Each membrane has its own set of lipids and proteins suited to that’s
membranes specific function.
Example: enzymes embedded in the membranes of my favorite organelle,
the mitochondria, and function in the process of cellular respiration.
Membranes are so fundamental and important to the organization of the cell,
we will devote all of chapter 7 to the membrane.
ANIMAL CELL
Cells do not really look like this.
Cell includes organelles – “little organs”.
Nucleus
Metabolic activities in the cytoplasm.
Cytosol the semifluid medium in cytoplasm.
ER
Not in animal cells: CHLOROPLASTS (PLASTIDS), CENTRAL VACUOLE, CELL
WALLS, PLASMODESMATA
PLANT CELL
A. Not in plant cells:
i. Lysosomes
ii. Centrosomes with centrioles
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B.
C.
D.
E.
Beavers Bio 6
iii. Flagella, though present in some plant sperm
Plastids – Chloroplasts (photosynthesis)
Large central vacuole or one or more small ones
Thick cell wall
Plasmodesmata
26.
NUCLEUS
A. Nucleus: (Do not confuse with the nucleus of an atom’s central core) the
chromosome containing organelle of a eukaryotic cell.
B. The nucleus contains most of the genes in the eukaryotic cell. Just to make
matters more confusing, some genes are located in the mitochondria and in
the chloroplasts.
27.
NUCLEAR ENVELOPE
A. Nuclear envelope: The double membrane in a eukaryotic cell that encloses
the nucleus, separating it from the cytoplasm.
B. Nuclear envelope is perforated by pore structures that regulate the entry
and exit of most proteins and RNA’s and large complexes of
macromolecules.
28.
NUCLEAR LAMINA
A. Nuclear lamina: A netlike array of protein filaments lining the inner surface
of the nuclear envelope- it helps maintain the shape of the nucleus.
29.
NUCLEUS - Chromosomes
A. Chromosomes: A cellular structure carrying genetic material, found in the
nucleus of eukaryotic cells. Each chromosome consists of one very long DNA
molecule and associated proteins. (A bacterial chromosome usually consists
of a single circular DNA molecule and associated proteins. It is found in the
nucleoid region, which is not membrane bounded.)
30.
NUCLEUS
Chromosomes and Chromatin
A. Chromatin: The complex of DNA and proteins that makes up a eukaryotic
chromosome. When the cell is not dividing, chromatin exists in its dispersed
form, as a mass of very long, thin fibers that are not visible with a light
microscope.
31.
32.
NUCLEUS - Chromatid
A. Chromatid (Sister Chromatids): (Not defined or discussed in this chapter)
either of two copies of a duplicated chromosome attached to each other by
proteins at the centromere and, sometimes along the arms. While joined,
two sister chromatids make up one chromosome; chromatids are eventually
separated during mitosis or meiosis II.
NUCLEUS - Nucleolus
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A. Nucleolus (pl. nucleoli): A specialized structure in the nucleus, consisting of
chromosomal regions containing ribosomal RNA genes along with ribosomal
proteins imported from the cytoplasm. It is the site of rRNA synthesis and
ribosomal subunit assembly.
33.
RIBOSOMES – (In and Out Burgers)
A. Ribosomes: A complex of rRNA and protein molecules that functions as a site
of protein synthesis in the cytoplasm; consists of a large and small subunit.
In eukaryotic cells, each subunit is assembled in the nucleolus.
34.
ENDOMEMBRANE SYSTEM
A. Endomembrane system: The collection of membranes inside and around a
eukaryotic cell related either through direct physical contact or by the
transfer of membranous vesicles; includes the nuclear envelope, smooth and
rough endoplasmic reticulum, the Golgi apparatus, lysosomes, vacuoles
(vesicles) and plasma membrane.
35.
VESICLES
A. Vesicle: A sac made of membrane in the cytoplasm.
36.
ENDOMEMBRANE SYSTEM
A. Endoplasmic reticulum (ER): An extensive membranous network in
eukaryotic cells, continuous with the outer nuclear membrane and composed
of ribosome-studded (rough) and ribosome free (smooth) region.
B. Smooth ER: That portion of the endoplasmic reticulum that is free of
ribosomes.
C. Rough ER: That portion of the endoplasmic reticulum studded with
ribosomes.
D. Synthesis of proteins
E. Protein Transport (within or out)
F. Metabolism & Movement of Lipids
G. Detoxification of Poisons
37.
ROUGH ER
A. Glycoproteins: A protein with one or more carbohydrates covalently attached
to it.
B. ROUGH ER
38.
ROUGH and SMOOTH ER
A. Transport vesicle: A tiny membranous sac in a cell’s cytoplasm carrying
molecules produced by the cell.
B. Smooth ER functions in diverse metabolic processes, which vary with cell
type.
i. Synthesis of lipids, metabolism of carbohydrates, detoxification of
drugs and poisons, storage of calcium ions.
39.
GOLGI APPARATUS
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A. Golgi apparatus (Golgi body, Golgi complex): An organelle in eukaryotic cells
consisting of stacks of flat membranous sacs that modify, store, and route
products of the endoplasmic reticulum and synthesize some products,
notably non-cellulose carbohydrates.
40.
LYSOSOME
A. Lysosome: A membrane-enclosed sac of hydrolytic enzymes found in the
cytoplasm of animal cells and some protists.
41.
LYSOSOMES WORKING PROPERLY
A. Lysosomes appropriately digest disabled organelles or tadpole tails or tissue
between an embryos webbed fingers.
42.
SYNDACTYLY: Syndactylism- a fusion of two or more toes and/or fingers.
43.
44.
What happens when the components of cells malfunction?
A. In lysosomal storage disorders, certain enzymes are deficient, leading to
accumulation of substrates (what they should digest) in lysosomes.
B. When lysosomes become engorged, they disrupt normal cell function.
C. Each lysosomal storage disorder is characterized by the type of substrate
that accumulates, and the cells, tissues or organs in which it accumulates.
LYSOSOMAL STORAGE DISORDERS - Hurler syndrome
45.
Children with Hurler syndrome begin to look like other affected children and
not like their own family.
46.
ENDOCYTOSIS – One Way Cells Take In Matter
A. Endocytosis: Cellular uptake of biological molecules and particulate matter
via formation of new vesicles from the plasma membrane.
B. ELECTRON MICROGRAPHS OF RECEPTOR-MEDIATED ENDOCYTOSIS
47.
PHAGOCYTOSIS
A. Phagocytosis: A type of endocytosis in which large particulate substances
are taken up by a cell. It is carried out by some protists and by certain
immune cells of animals (in mammals, mainly macrophages, neutrophils,
and dendritic cells).
B. “Cell eating”. Moves large particles even whole micro-organisms, into cells.
48.
PHAGOCYTOSIS
A. Parasite and macrophage
49.
EXOCYTOSIS
A. Exocytosis: The process in which intracellular material is enclosed within a
membrane-bound sac that moves to the plasma membrane and fuses with
it, releasing the material outside the cell.
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50.
FOOD VACUOLES
A. Food vacuoles: A membranous sac formed by phagocytosis of
microorganisms or particles to be used as food by the cell.
51.
CONTRACTILE VACUOLE
A. Contractile vacuole: A membranous sac that helps move excess water out of
certain fresh-water protists.
52.
CENTRAL VACUOLE
A. Central vacuole: A membranous sac in a mature plant cell with diverse roles
in reproduction, growth, and development.
B. ¾ or more of the volume of many plant cells is occupied by LARGE CENTRAL
VACUOLE.
53.
TURGOR PRESSURE: Turgor pressure: pressure developed within a cell
(especially the central vacuole of plant cells) as a result of osmotic water entry (to
be discussed soon). End of endomembrane discussion.
54.
TOUR OF THE CELL – ENERGY TRANSFER
A. Mitochondria: (s. mitochondrion) an organelle in eukaryotic cells that serves
as the site of cellular respiration.
B. Eukaryotes: mitochondria and chloroplasts convert energy to useable forms.
55.
TOUR OF THE CELL – ENERGY TRANSFORMER
A. Chloroplast: An organelle found in plants and photosynthetic protists that
absorbs sunlight and uses it to drive the synthesis of organic compounds
from carbon dioxide and water.
B. Chloroplasts typically have three membranes separating their innermost
space from cytosol (the fluid of the cell).
56.
DNA IN MITOCHONDRIA AND CHLOROPLAST
A. Both mitochondria and chloroplast contain a small amount of DNA.
B. Their DNA programs the production of proteins made on the organelles
ribosomes.
57.
MORE MITOCHONDRIA
A. Found in almost all eukaryotic cells: plants, animals, fungi, and most
protists.
B. Site of cellular respiration.
C. A cell usually has hundreds-thousands of mitochondria but some cells have a
single large one. Number of mitochondria correlates with?
58.
MORE ON MITOCHONDRIA
A. Cristae (s. crista): An infolding of the inner membrane of a mitochondrion
that houses electron transport chains and molecules of the enzyme
catalyzing the synthesis of ATP (ATP synthase).
59.
WRAP UP MITO
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A. Mitochondrial matrix: The compartment of the mitochondrion enclosed by
the inner membrane and containing enzymes and substrates for the citric
acid cycle.
B. What does increased surface in the matrix enhance?
60.
FAMILY OF PLANT ORGANELLES
A. Plastids: One of a family of closely related organelles that includes
chloroplasts, chromoplasts, and amyloplasts (leucoplasts). Plastids are found
in cells of photosynthetic organisms.
61.
THE CHLOROPLAST
A. Thylakoid: A flattened membranous sac inside a chloroplast. Thylakoids exist
in an interconnected system in the chloroplast and contain the molecular
“machinery” used to convert light energy to chemical energy.
62.
CHLOROPLAST
A. Granum (pl. grana): a stack of membrane-bounded thylakoids in the
chloroplast. Grana function in the light reactions of photosynthesis.
B. Stroma: Within the chloroplast, the dense fluid of the chloroplast
surrounding the thylakoid membrane; involved in the synthesis of organic
molecules from carbon dioxide and water.
63.
PEROXISOMES
A. Peroxisome: An organelle containing enzymes that transfer hydrogen (H2)
from various substrates to oxygen (O2), producing and then degrading
hydrogen peroxide (H2 O2).
64.
Cytoskeleton:
A. A network of microtubules, microfilaments, and intermediate filaments that
branch through the cytoplasm and serve a variety of mechanical, transport,
and signaling functions.
65.
POISONS AND CYTOSKELETONS
A. Autumn crocus: produces colchicine: blocks microtubule assembly in cells of
animals.
B. Western Yew: makes taxol, also a microtubule poison used to stop cell
division of cancer cells.
66.
CELL MOTILITY
A. Motor proteins: A protein that interacts with cytoskeletal elements and other
cell components, producing movement of the whole cell or parts of the cell.
B. Includes cell movement in location and the more limited movement of the
parts within the cell.
67.
MOTOR PROTEINS THAT ATTACH TO RECEPTORS ON VESICLES CAN WALK
THE VESICLES ALONG MICROTUBULES.
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A. Cytoskeletal elements and motor proteins work together with plasma
membrane molecules to allow whole cells to move along fibers outside the
cell.
68.
MICROTUBULES
A. Microtubules: A hollow rod composed of tubulin proteins that make up part
of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella.
69.
THE WORK OF MICROTUBULES
A. Centrosome: Structure present in the cytoplasm of animal cells, important
during cell division; functions as a microtubule organizing center. A
centrosome has two centrioles.
B. Centrioles: A structure in the centrosome of an animal cell composed of a
cylinder of microtubule triplets arranged in a 9 + 0 pattern. A centrosome
has a pair of centrioles.
70.
FLAGELLUM
A. Flagella (s. flagellum): A long cellular appendage specialized for locomotion.
Like motile cilia, eukaryotic flagella have a core with nine outer doublet
microtubules and two inner single microtubules ensheathed in an extension
of the plasma membrane. Prokaryotic flagella have a different structure.
71.
CILIA
A. Cilia (s. cilium): A short cellular appendage containing microtubules. A
motile cilium is specialized for locomotion and is formed from a core of nine
outer doublet microtubules and two inner single microtubules (the “9 + 2”
arrangement) ensheathed in an extension of the plasma membrane. A
primary cilium is usually nonmotile and plays a sensory and signaling role; it
lacks the two inner microtubules (the “9 + 0” arrangement).
72.
Arrangement in the ultrastructure of a eukaryotic flagellum or motile cilium.
A. In humans and many animals the basal body of the fertilizing sperm enters
the egg and becomes a centriole.
73.
BASAL BODY
A. Basal body: A eukaryotic cell structure consisting of a “9 + 0” arrangement
of microtubule triplets. The basal body may organize the microtubule
assembly of a cilium or flagellum and is structurally very similar to a
centriole.
74.
COMPARING THE BEATING OF FLAGELLA AND CILIA
A. Cilia works like the oars of a boat or arms of a swimmer.
B. Flagella works like a motor behind a rowboat.
75.
MOTOR PROTEINS
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A. Dynein: In cilia and flagella, a large contractile protein extending from one
microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes
in dynein shape that lead to bending of cilia and flagella.
B. Dynein (dI-nE-un): Responsible for the bending movements of the organelle
– ATP provides the energy.
76.
MICROFILAMENT
A. Microfilament: A cable composed of actin proteins in the cytoplasm of almost
every eukaryotic cell, making up part of the cytoskeleton and acting alone or
with myosin to cause cell contraction; also known as an actin filament.
B. Actin: A globular protein that links into chains, two of which twist helically
about each other forming microfilaments (actin filaments) in muscle and
other kinds of cells.
C. Microfilaments are the thinnest.
D. Microfilaments are a twisted double chain
77.
MICROFILAMENTS
A. A twisted double chain of actin subunits.
B. Cortical microfilaments help to support the shape of the cell.
C. The microfilament bears tension.
78.
CORTEX: The outer cytoplasmic layer of a cell
A. Cortex: The outer region of cytoplasm in a eukaryotic cell, lying just under
the plasma membrane, that has a more gel-like consistency than the inner
regions, due to the presence of multiple microfilaments. (A different
definition in plants).
B. Myosin: A type of protein filament that acts as a motor protein with actin
filaments to cause cell contraction.
79.
FALSE FEET and MOVEMENT
A. Pseudopods, or “false feet”: A dynamic lobe of membrane-enclosed
cytoplasm; functions in motility and capture of prey.
B. Microfilaments that elongate in the lobe also push it forward.
C. Localized contraction brought about by actin and myosin also plays a role in
amoeboid movement in which a cell such as an amoeba crawls along a
surface by extending and flowing into cellular extensions called pseudopodia,
or false foot.
D. It is thought that filaments near the cell’s trailing end interact with myosin,
causing contraction, like squeezing a toothpaste tube would cause the fluid
to push forward.
80.
INTERMEDIATE FILAMENTS
A. INTERMEDIATE FILAMENTS: a component of the cytoskeleton that includes
filaments intermediate in size between microtubules and microfilaments.
81.
Cell walls: A protective layer external to the plasma membrane in the cells of
plants, prokaryotes, fungi, and some protists. Polysaccharides such as cellulose (in
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plants and some protists), chitin (in fungi), and peptidoglycan (in bacteria) are an
important structural component of cell walls.
82.
CELL WALLS
A. PRIMARY CELL WALLS: In plants, a relatively thin and flexible layer first
secreted by a young cell.
B. MIDDLE LAMELLA: In plants, a thin layer of adhesive extracellular material,
primarily pectin, found between the primary walls of adjacent young cells.
C. SECONDARY CELL WALL: In plants, a strong and durable matrix often
deposited in several laminated layers for cell protection and support.
83.
EXTRACELLULAR MATRIX: The substance in which animal cells are
embedded, consisting of protein and polysaccharides synthesized and secreted by
cells.
A. COLLAGEN: A glycoprotein in the extracellular matrix of animal cells that
forms strong fibers, found extensively in connective tissue and bone; the
most abundant protein in the animal kingdom.
84.
PROTEINS
A. Proteoglycan: A glycoprotein consisting of a small core protein with many
carbohydrate chains attached, found in the extracellular matrix of animal
cells. A proteoglycan may consist of up to 95% carbohydrate.
B. Fibronectin: A glycoprotein that helps animal cells attach to the extracellular
matrix.
C. Integrin: In animal cells, a transmembrane receptor protein that
interconnects the extracellular matrix and the cytoskeleton.
85.
A.
B.
C.
D.
INTERCELLULAR JUNCTIONS
Plasmodesmata (s. plasmodesma): An open channel in the cell wall of a
plant through which strands of cytosol connect from an adjacent cell.
TIGHT JUNCTIONS
DESMOSOMES (anchoring junctions)
GAP JUNCTIONS (communicating junctions)