Histology - Anatomy of the Cell (1) Flashcards
What is a cell?
A cell is a BASIC STRUCTURAL UNIT of living things.
What is the % composition of a cell?
80% H2O ** 15% Protein ** 2.5% Lipid 1.5% Carbohydrate 1.0% Inorganic
**mostly
What are the 5 basic features common to eukaryotic cells?
OUTER MEMBRANE INNER CYTOSOL CYCLOSKELETON ORGANELLES INCLUSIONS
What is Cytosol?
Solution of:
Proteins
Electrolytes
Carbohydrates
Fluid and gel-like
What is a Cycloskeleton?
Determines SHAPE and FLUIDITY
Made from INTERMEDIATE FILAMENTS and MICROTUBULES
Where are membrane bound organelles found?
Cytosol.
What are Inclusions?
Structures found in the CYTOPLASM which may/may not be bound by a membrane.
What does the Plasmalemma do?
The Plasmalemma separates the CYTOPLASM from the OUTSIDE environment.
What kind of layer does the Plasmalemma have?
BI-LAYER.
What kind of property does the Plasmalemma have?
AMPHIPATHIC properties.
What does AMPHIPATHIC mean?
Amphipathic means it has both hydrophobic and hydrophilic parts.
i.e. fat molecules with heads and tails
Where are the heads and tails positioned in the Plasmalemma?
The heads are located outside while the tails face inwards.
In the Plasmalemma the tails are…
HYDROPHOBIC
They are water-hating.
They are repelled by water.
In the Plasmalemma the heads are…
HYDROPHILLIC
They are water-loving.
They are attracted to water.
What kind of proteins are found in the Plasmalemma?
INTEGRAL PROTEINS
What kind of integral proteins are found in the Plasmalemma? Name five.
Receptors Transporters Channels Enzymes Cell Attachment Proteins
Describe the permeability of the cell membrane.
SELECTIVELY PERMEABLE.
What is EXOCYTOSIS?
The process by which material LEAVES via the cell membrane.
What is ENDOCYTOSIS?
The process by which material ENTERS the cell via cell membrane.
What molecules can easily diffuse into the cell via the cell membrane?
H2O
CO2
What does the cytoplasm contain?
The cytoplasm contains structures which may be identified when observed via a microscope.
What factors does identifying structures on a microscope depend on when identifying them through a microscope?
SIZE
SHAPE
STAIN
What is an organelle?
“A small, intracellular organ essential to life”
What do MITOCHONDRIA do?
Mitochondria are ENERY-PRODUCING.
What is the ROUGH ENDOPLASMIC RETICULUM involved in?
rER are involved in PROTEIN SYNTHESIS.
What is the SMOOTH ENDOPLASMIC RETICULUM involved in? (3)
Cholesterol Synthesis
Lipid Synthesis
Detoxification
Name the function of the Golgi Apparatus.
Modification of Secretions
Packaging of Secretions
What is the function of Lysosymes?
They contain HYDROLYTIC ENZYMES for intracellular digestion.
What does the NUCLEUS contain?
The nucleus contains the GENETIC CODE.
What are CYCLOSKELETAL PROTEINS?
They are FILAMENTOUS CYTOSOLIC PROTEINS.
They maintain several functions of the cell.
What are the three main classes of CYTOSKELETAL PROTEINS?
MICROFILAMENTS
INTERMEDIATE FILAMENTS
MICROTUBULES
What is the order of CYTOSKELETAL PROTEINS in decreasing size?
MICROTUBULES
INTERMEDIATE FILAMENTS
MICROFILAMENTS
What are Microfilaments composed of?
Microfilaments are composed of the protein ACTIN.
What is the diameter of microfilaments?
7nm
What is a key characteristic of Microfilaments?
They are VERY DYNAMIC.
The Actin within them dissociates later after it assembles.
What is the function of the Intermediate Filaments? (2)
- Bind intracellular elements together.
- Bind intracellular elements to the Plasmalemma.
Roughly how many types of Intermediate Filaments are there?
Around 50!!
What is a rough estimate of size of Intermediate Filaments?
10-15nm in diameter.
Describe the appearance of a Microtubule. (3)
- Hollow tubule.
- Composed of 2 tubulin subunits.
- Can be assembled/disassembled.
Where do microtubules originate from?
Microtubules originate from the microtubule organising centre, CENTROSOME.
In what cell features are Microtubules important in?
CILLIA
FLAGELLA
MITOTIC SPINDLES
What encloses the NUCLEUS?
A NUCLEAR ENVELOPE.
How many membranes is the nucleus composed of?
TWO.
Name the TWO membranes the nucleus is composed of.
INNER MEMBRANE
OUTER MEMBRANE
What does the OUTER nuclear membrane have?
A NUCLEAR PORE.
What is the function of the nuclear pore?
The nuclear pore provides an exit for mRNA.
What is found between the two sheets of the nucleus?
PERINUCLEAR CISTERN.
What is the perinuclear cistern continuous with?
The perinuclear cistern is continuous with the CISTERN OF THE rER.
What is the nuclear membrane studded with?
The nuclear membrane is studded with RIBOSOMES.
What is the nucleus a location of?
RIBOSOME SYNTHESIS.
What does the nucleus contain?
DNA
CHROMOSOMES
GENETIC MATERIAL
What is transcribed in the nucleus?
mRNA
tRNA
Where is rRNA transcribed?
rRNA is transcribed in the NUCLEOLUS.
What is the nucleolus?
The nucleus is a dense area in the nucleus.
What does the nucleus contain?
EUCHROMATIN
HETEROCHROMATIN
What is EUCHROMATIN?
DNA that is more DISPERSED
ACTIVELY TRANSCRIBING
What is HETEROCHROMATIN?
DNA that is highly CONDENSED
NOT UNDERGOING TRANSCRIPTION
What two subunits are Ribosomes made up of?
SMALL SUBUNIT
LARGE SUBUNIT
What does the Small subunit do?
BINDS RNA
What does the Large subunit do?
Catalyses the formation of PEPTIDE BONDS.
What are the two types of ENDOPLASMIC RETICULUUM?
rER
sER
What is the Endoplasmic Reticuluum?
A NETWORK INTERCONNECTING MEMBRANE BOUND COMPARTMENTS IN A CELL.
Why does the presence of the rER vary?
It varies based on CELL ACTIVITY - if a cell is more active it will have more rER, if less active then less rER.
What are POLYSOMES?
They are many ribosomes stuck together.