Cell Structure And Organisation Flashcards
What is a prokaryotic cell?
No proper nucleus
Just a chromosome
E.g. Bacteria and Cyanobacteria
What is a Eukaryotic cell?
True nucleus with double membrane
Larger than prokaryotic
Contain membrane bound organelles
What are the different types of electron microscopes?
-transmission electron microscope:
View cross section of cells
-scanning electron microscope:
Spray specimen with thin layer of gold-gives 3D shape
Specimen is in vacuum so can’t see living things or colour
Definition of tissue
Group of cells with the same function and structure working together
Definition of organ
Several tissues working together, performing a specific function
Epithelial tissue
- Forms a continuous layer- covering or lining the internal or external surfaces of the body
- No blood vessels
- May have nerve ending
- Cells sit in basement membrane
- Made of collagen and protein
- Often have protective or secretory function
Epithelial tissue: cuboidal tissue
-cube shape
-one cell thick
E.g. Proximal convoluted tubule of kidney nephron
Ducts of salivary gland
Epithelial tissue:
Columnar epithelium
- Elongated cells
- lining tubes that substances move through have cilia(eg Fallopian tube and trachea)
Epithelial cells:
Squamous epithelium
- consists of flattened cells on a basement membrane
E.g. Walls of the alveoli
Line the bowmans capsule
Muscle tissue:
Skeletal muscle
- attached to bones
- generates locomotion in mammals
- bands of long cells which give powerful contractions
- muscle tires easily
- voluntary muscles
- also called striped and striated- can see stripes on them in microscope
Muscle tissue:
Smooth muscle
- individual spindle shaped cells
- can contract rhythmically, but less powerful than skeletal muscle
- occur in: skin, walls of blood vessels, digestive and respiratory tracts
- involuntary muscles
- unstriped/ unstriated
Muscle tissue:
Cardiac muscle
- Only found in the heart
- does not tire
- contract rhythmically without any stimulation from nerves or hormones
Connective tissue
- supports/separates tissues and organs
- contains elastic and collagen fibres in extra cellular fluid and matrix
- between fibres are fat storing cells: adipocytes
Definition of resolution
The smallest distance between two points that can be separately distinguished.
Structure of Golgi body
- similar to ER but more compact
- stack of membranes which form flattened sacs called cisternae
Functions of golgi body
- producing secretory enzymes
- modifying/ packaging proteins
- secreting carbohydrates
- producing glycoprotein
- transporting and storing lipids
- forming lysosomes
Structure of endoplasmic reticulum
Composed of fluid filled sacs called cisternae
Describe rough ER
Ribosomes on outer surface and transports proteins made there
Present in large amounts in cells that make a lot of protein
Describe smooth ER
Comprises membranes that lack ribosomes
Associated with synthesis and transport of lipids
Describe lysosomes
- small temporary vacuoles surrounded by single membrane
- formed from Golgi body
- isolate potentially harmful digestive enzymes
- enzymes released when cell recycles organelles
Describe mitochondria
- double membrane - inter membrane space
- inner membrane folded inwards- Cristae
- produce ATP
Describe centrioles
- located just outside nucleus
- 2 rings of microtubles, making hollow cylinders positioned at right angles
