PRELIMS CYTO TOPIC 3

Cells and extracellular material

together comprise the tissues that make up animal organs.

cells

are the basic structural and functional units, the smallest living parts of the body.

Animal cells, eukaryotic

are enclosed by cell membranes and are ____, each with a distinct, membrane-enclosed nucleus surrounded by cytoplasm, fluid containing a system of membranous organelles, nonmembra-nous molecular assemblies, and a cytoskeleton.

prokaryotic cells of bacteria

typically have a cell wall and lack nuclei and membranous cytoplasmic structures.

PROKARYOTIC CELL

• Are cells without a nucleus. The DNA in prokaryotic cells is in the cytoplasm
  rather than enclosed within a nuclear membrane.
  -____are found
  in single-celled organisms, such as bacteria
  Example: Bacteria
  ● Staphylococcus aureus
  ● Streptococcus pyogenes
  ● Escherichia coli
  ● Mycobacterium tuberculosis

EUKARYOTIC CELL

• cells that contain a nucleus.
• also contain membrane-bound
  organelles besides the nucleus.

Organelle

• a structure within the cytoplasm
  that performs a specific job in the
  cell.

1. Carbohydrates (Sugars and
   Starches)
2. Lipids (Fats and Oils)
3. Proteins
4. Nucleic acids (DNA and RNA)

3 major macromolecules of the cells:

CARBOHYDRATES

• provide energy and contribute to cell structure.

LIPIDS

• form the basis of several types of
  hormones, form membranes, provide
  insulation and store energy

PROTEINS

• Blood clotting, nerve transmission, and
  muscle contraction

• Antibodies

what proteins fight bacterial infection

• Enzymes

are proteins that facilitate or
catalyze biochemical reactions

NUCLEIC ACIDS

• DNA and RNA translate information from
  past generations into specific collections
  of proteins that give a cell its individual
  characteristics

PLASMA MEMBRANE

• (cell membrane
  or plasmalemma) that envelops every
  eukaryotic cell consists of phospholipids,
  cholesterol, and proteins, with
  oligosaccharide chains covalently linked
  to many of the phospholipids and
  proteins.
• This limiting membrane functions as a
  selective barrier regulating the passage
  of materials into and out of the cell and
  facilitating the transport of specific
  molecules

CYTOSKELETON

• Maintains intracellular structural support
  and organization of cells; participates in
  cell division; facilitates movement

microtubules
actin Filaments or microfilaments
intermediate filaments

• CYTOSKELETON Contains three types of polymers:

(1)microtubules

25 nm in diameter;

(2) actin filaments or microfilaments

(5-7 nm);

(3) intermediate filaments

(8-10 nm).

CYTOPLASM

• The inner fluid component of the cell
  therwise known as Cytosol,
  houses/bathes the organelles
• Cytosol also contains hundreds of
  enzymes

RIBOSOME

• are macromolecular machines that
  assemble polypeptides from amino acids
  on molecules of transfer RNA (tRNA) in a
  sequence specified by mRNA
• Organelle that acts as the site of protein
  synthesis.
• Located at the Rough Endoplasmic
  Reticulum (RER)

Amino acids

building blocks of
proteins

ENDOPLASMIC RETICULUM

• The ER is a major site for vital cellular
  activities, including biosynthesis of
  proteins and lipids.
• Numerous Ribosomes attached to the
  membrane in some regions of ER allow
  two types of ER to be distinguished

Smooth Endoplasmic Reticulum
(SER)

○ Biosynthesis of Lipids
-Regions of ER that lack bound
polyribosomes make up the
smooth endoplasmic reticulum
(SER), which is continuous with
RER but frequently less abundant

• Also create proteins (enzymes)
  that perform synthesis of
  phospholipids and steroids, allows
  detoxification, and sequestration
  an controlled release of Calcium

● Rough Endoplasmic Reticulum
(RER)

○ Biosynthesis of Proteins
○ Studded with Ribosome
-Pancreatic acinar cells (making
digestive enzymes), fibroblasts
(collagen), and plasma cells
(immunoglobulins

GOLGI APPARATUS

• Otherwise known as Golgi complex
• Completes posttranslational
  modifications of proteins produced in the
  RER and then packages and addresses
  these proteins to their proper
  destinations

SECRETORY GRANULES

• Originating as condensing vesicles in the
  Golgi apparatus, secretory granules are
  found in cells that store a product until
  its release by exocytosis.

• Primary lysosomes

emerge from the
Golgi apparatus containing inactive acid
hydrolases specific for degrading a wide
variety of cellular macromolecules.

• Secondary lysosomes

are more
heterogeneous, having fused with
vesicles produced by endocytosis that
contain material to be digested by the
hydrolytic enzymes.

PROTEOSOMES

• are small cytoplasmic
  protein complexes which degrade
  improperly folded proteins after they are
  tagged with the polypeptide ubiquitin.

PEROXISOMES

• are small spherical
  organelles containing enzymes for
  various metabolic reactions, notably for
  oxidation and detoxification, and catalase
  that breaks down the H202 resulting
  from those reactions

● Vesicles/granules

contains
protein to be secreted via
exocytosis

● Lysosomes

Contains enzymes.
Binds with endocytosed vesicles
for digestion.

● Proteosome

Degrade improperly
folded proteins

MITOCHONDRIA

• Powerhouse of the cell
• Are the major sites of ATP synthesis and
  are abundant in cells or cytoplasmic
  regions where large amounts of energy
  are expended

CENTROSOME

• Amorphous region adjacent to nucleus;
  contains a pair of centrioles
• Organizes microtubules; participates in
  mitotic spindle formation during cell
  division

NUCLEUS

• Typically the largest structure within a
  cell. it consists of a nuclear envelope
  containing chromatin, the mass of DNA
  and its associated proteins, with one or
  more specialized regions of chromatin
  called nucleoli.

NUCLEAR ENVELOPE

• Forms a selectively permeable barrier
  between the nuclear and cytoplasmic
  compartments

CHROMATIN

• consists of DNA and all of the
  associated proteins involved in the
  organization and function of DNA.
• In humans, each cell's ___ (except
  that of eggs and sperm) is divided
  among 46 chromosomes (23 pairs)

NUCLEOLUS

• is a generally spherical,
  highly basophilic subdomain of nuclei in
  cells actively engaged in protein
  synthesis
• The basophilic color of the is
  due to the abundance of RNA
  (Ribonucleic Acid)