Cells And Tissues Flashcards
What are cells
The cell is the basic unit of all organisms
Has a highly organised structure which enables it to carry out its vital functions
Key scientist of cell theory
Robert Hooke
Theodore Schwann
Matthias Schleiden
Rudolf Virchow
Three principles of cell theory
All living things are made up of one or more cells
Cells are the most basic unit of structure and function in all living things
All cells are created by pre-existing cells
Prokaryotic cells
Bacteria and Archaea.
Amongst the simplest of organisms and made of single cells (unicellular).
Cell membrane, cytoplasm, no membrane-bound organelles, and DNA is free-floating in cytoplasm.
Cell division by binary fission.
Most are 0.2-2.0 μm.
Eukaryotic cells
Animal, Plant, Protist and Fungal.
More complex cells, made of many cells (multicellular).
Cell membrane, cytoplasm, cell organelles, and DNA within a nucleus.
Cell division by mitosis.
Most are 5-100 μm.
Structure of organelles
Nucleus
Mitochondria
Ribosomes
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Golgi apparatus, and Golgi vesicles
Centrioles
Lysosomes
Organism
An individual plant, animal or single-celled lifeforms
Organelles
Specialised structures within the cell that have specific functions
Cytoplasm
The fluid component of the cell, enclosed by the cell membrane and surrounding
the organelles
Membrane
All membranes consist of a phospholipid bilayer together with proteins and other
components. They are selectively permeable and can control movement of substances across
the membrane as well as being the sites of many important processes in the cell
Phospholipid
Large molecule formed from a glycerol molecule covalently bound to two fatty
acid molecules and a phosphate group
Phospholipid bilayer
: A double layer of phospholipids with the hydrophobic tails arranged
towards the middle and the hydrophilic head group on the outside. Forms the basis of all biological membranes
Hydrophlilic
Can interact with Water
Hydrophobic
Repels water
Erythrocytes
(red blood cells) carry oxygen around the body, by using haemoglobin. The cells lack a nuclei and most other organelles so it has more room for haemoglobin. They are flattened and biconcave in shape, which increases the surface area of the cell, allowing more efficient diffusion of oxygen. The elastic plasma membrane allows the cell to change shape and squeeze through narrow capillaries
Neurones
nerve cells are highly specialised to enable them to conduct electrical impulses in the nervous system. The impulse occurs in one direction, with sensory neurones in the peripheral nervous system (PNS) conducting impulses towards the central nervous system (CNS), and motor neurones conducting impulses away from the CNS
Squamous Epithelial Cells
most important feature is that they are flattened cells, supported by a basement membrane, which makes up the epithelium. They are well suited to exchange surfaces, such as in the lungs. The basement membrane is a thin layer of protein fibres and polysaccharides which help support the epithelium (it is not a phospholipid bilayer like cell membranes)
Erythrocytes
Carry oxygen haemoglobin it lacks a nuclei they are flattened and bisonaux this increases its surface area it can also change shape which allows it to squeeze through narrow capillaries
Neurones
Sensory neurones- peripheral nervous system (PNS)
Central nervous system (CNS)
Motor neurones
Squamous epithelial cells
Flattened cues supported by a basement membrane - the basement is a thin layer of protein fibres
Totipotent
Can divide to produce any body cell
Pluripotent
Found in embryos can divide and create tumours
Multipotent
Found in mature mammals (adults) CG bone marrow can differentiate into limited number of cells- can differentiate late into limited number of cell- can. Differentiate I to erythrocytes (erythropoiesis)
Endoderm
Lungs, liver, pancreas, small intestine, large intestine, stomach
Mesoderm
Muscle, bone, heart cell, inner lining of skins, kidneys, bladder, ovaries, testicles
Ectoderm
Outer layer of skin- sweat glands, hair, nervous system
Specialised blood cells
Haemotoposes (haem=blood) haemotopolleic stem- found in bone marrow in adults (lymphopolesis)
Embryos
Up to 16 days after fertilisation
Umbilical cord blood
Contains multi potent
Placenta
Can develop into limited number of specialised cells
Adult stem cells
Bone marrow= repair
Epigenetic’s
is the study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself In its modern sense, epigenetics is the term used to describe inheritance by mechanisms other than through the DNA sequence of genes
Mitosis
is a process where a single cell divides into two identical daughter cells
Stages of mitosis
Prophase: the stage in which chromosomes become
visible and the nuclear envelope disappears
Metaphase: the chromosomes arrange themselves at the centre of the cell
Anaphase: each of the two threads of chromosomes
(chromatid) migrates to the opposite pole
Telophase: the nuclear envelope reforms to produce two daughter cells
What does PMAT stand for
Prophase
Metaphase
Anaphase
Telophase
Stages of the cell cycle
Interphase
Mitosis
Cytokinesis
Prokaryotic
Bacteria
Eukaryotic
Animal
Plant
Haematopoiesis
A pathway where haematopoietic stem cells, which are found in the
bone marrow of adults, can differentiate into blood cells.
Mitosis
is a process where a single cell divides into two identical daughter cells.
The cell cycle
is a series of events that take place in a cell, as it grows and divides.
Stages of the Cell Cycle
• Interphase
• Mitosis and Cytokinesis
Standard Form
A standardised system of writing numbers, which is useful when working with a very large and small
numbers.
Three key types of microscopes
• Optical (Light) Microscope
• Transmission Electron Microscope
• Scanning Electron Microscope
Light Microscope
• The light microscope is used to visualise small structures
and samples by magnifying image of how they interact with
visible light, e.g. reflect, absorb or scatter
• Used to visualise fine detail of an object, reading a
magnified image through a series of glass lenses, which first
focus a beam of light onto or through an object, and convex
objective lenses to enlarge the image formed
• Poorer resolution to electron microscopes, due to light
having longer wavelength
• Lower magnification
• Colour images
• Can view living samples
Electron Microscope
• A beam of electrons condense by electromagnets to
create an image
• Has a higher resolving power due to electrons having
a short wavelength
• Higher magnification
• Black and white images
• Samples placed in vacuum, therefore non-living
Magnification
is how many times bigger
the image of a specimen observed is in
comparison to the actual size of the
specimen.
Calculating Magnification
Magnification =Size of image divided by Size of object
Eyepiece Graticule
• When looking through an optical microscope,
there is a scale on a glass disc known as the
eyepiece graticule
• This helps when measuring the size of objects
being viewed under the microscope
• This needs to be calibrated each time you
change the objective lens and magnification
• To calibrate, you use a stage micrometre
Calculating TOTAL Magnification
Eyepiece Lens x Objective Lens =Total Magnification
