Cellular Structure and Function
Monday, 14th February 2022
Intro to Cells:
Compounds form molecules to form cells which form tissues that form organs
that collectively form systems which leads to the human body.
Cell theory is that cells are the building blocks of living organisms and that all
cells are formed from pre-existing cells and that they maintain homeostasis.
They are the most fundamental unit of life.
The human body has two types of cell classes, somatic or body cells, and
gametic or sex cells.
Cells are composed of three main parts, the plasma membrane the cytoplasm
consisting of the cytosol and organelles and finally the nucleus that stores the
genetic information.
Plasma Membrane:
Separates the cytoplasm from the extracellular fluid.
Semi-permeable and controls traffic into and out of the cell.
Consists of phospholipids, cholesterol and proteins.
Phospholipids have the phobic tail and philic head forming the bilayer and
proteins allow for the active movement if large or polar molecules.
Cholesterol aids in the strength and permeability of the membrane and
function of the integral (spanning) and peripheral (embedded) proteins.
The membrane is a physical barrier and protects the cell, controls movement
into and out of the cell, sensitive to the internal and external environment and
with the aid of the cellular skeleton provide structural support.
Microvilli:
Finger-like extensions of the cell membrane containing actin microfilaments.
Cellular Structure and Function 1
, They increase surface area of the cell membrane to aid in absorption.
They are found in areas where rapid absorption takes place, like the intestinal
lumen and the kidneys where ultrafiltration takes place.
Cilia:
Similar structure to the villi, however they perform a motor function by moving
fluids and mucous.
Present in the respiratory tracts and the reproductive system (egg to uterus).
Nicotine paralyses cilia and leads to the ‘smoker’s cough’.
Flagella:
Similar in structure to cilia, but much longer.
Only found on sperm cells in humans and is a single whiplike structure that
moves in a helical fashion to propel the sperm cell to the egg.
Cytoplasm:
The gelatinous fluid between the plasma membrane and the nuclear envelope.
Contains the cytosol and organelles, as well as nutrients, ions, proteins, waste
and fibres.
The cytosol is the site of many cellular reactions.
Cytoskeleton:
The framework of the cell that provides strength, flexibility and mobility.
Microfilaments are the smallest and composed of actin and myosin proteins.
Anchor and attach the plasma membrane to the cytoplasm itself.
Move and deform to change the shape of the cell.
Intermediate filaments are very strong and help to strengthen the cell and
provide anchoring and positioning for the organelles.
Microtubules are large, hollow tubes composed of tubulin.
Determine cell shape, movement of secretory vesicles and the
chromosomes during division.
Also present in cilia and flagella.
Centrioles:
Cellular Structure and Function 2
Monday, 14th February 2022
Intro to Cells:
Compounds form molecules to form cells which form tissues that form organs
that collectively form systems which leads to the human body.
Cell theory is that cells are the building blocks of living organisms and that all
cells are formed from pre-existing cells and that they maintain homeostasis.
They are the most fundamental unit of life.
The human body has two types of cell classes, somatic or body cells, and
gametic or sex cells.
Cells are composed of three main parts, the plasma membrane the cytoplasm
consisting of the cytosol and organelles and finally the nucleus that stores the
genetic information.
Plasma Membrane:
Separates the cytoplasm from the extracellular fluid.
Semi-permeable and controls traffic into and out of the cell.
Consists of phospholipids, cholesterol and proteins.
Phospholipids have the phobic tail and philic head forming the bilayer and
proteins allow for the active movement if large or polar molecules.
Cholesterol aids in the strength and permeability of the membrane and
function of the integral (spanning) and peripheral (embedded) proteins.
The membrane is a physical barrier and protects the cell, controls movement
into and out of the cell, sensitive to the internal and external environment and
with the aid of the cellular skeleton provide structural support.
Microvilli:
Finger-like extensions of the cell membrane containing actin microfilaments.
Cellular Structure and Function 1
, They increase surface area of the cell membrane to aid in absorption.
They are found in areas where rapid absorption takes place, like the intestinal
lumen and the kidneys where ultrafiltration takes place.
Cilia:
Similar structure to the villi, however they perform a motor function by moving
fluids and mucous.
Present in the respiratory tracts and the reproductive system (egg to uterus).
Nicotine paralyses cilia and leads to the ‘smoker’s cough’.
Flagella:
Similar in structure to cilia, but much longer.
Only found on sperm cells in humans and is a single whiplike structure that
moves in a helical fashion to propel the sperm cell to the egg.
Cytoplasm:
The gelatinous fluid between the plasma membrane and the nuclear envelope.
Contains the cytosol and organelles, as well as nutrients, ions, proteins, waste
and fibres.
The cytosol is the site of many cellular reactions.
Cytoskeleton:
The framework of the cell that provides strength, flexibility and mobility.
Microfilaments are the smallest and composed of actin and myosin proteins.
Anchor and attach the plasma membrane to the cytoplasm itself.
Move and deform to change the shape of the cell.
Intermediate filaments are very strong and help to strengthen the cell and
provide anchoring and positioning for the organelles.
Microtubules are large, hollow tubes composed of tubulin.
Determine cell shape, movement of secretory vesicles and the
chromosomes during division.
Also present in cilia and flagella.
Centrioles:
Cellular Structure and Function 2
