Cells, Celluar Organsiation Flashcards
What is an organ
Collection of tissues that are adapted to perform a particular function
Organ systems
Large multicellular organisms are called organ systems
Composed of a number of organs working together to carry out major functions
E.g digestive , cardiovascular, gas exchange
Structure and function of erythrocytes
Flattened biconcave shaped discs increases SA
No nuclei and few organelles, increases SA for haemoglobin
Flexible- so can fit through capillaries
Structure and function of neutrophils
Essential role in the immune system
Multi lobed nucleus, makes it easier for them to squeeze through small gaps to get to site of infection
Many lysosomes in cytoplasm used to attack pathogens
Structure and function of sperm cells
Deliver genetic information to the female gamete
Have a flagellum, capable of movement
Contain many mitochondria to provide the energy needed to swim
Acrosome on the head of speed contains digestive enzymes which are released to digest the protective layers around the ovum
Structure and function of palisade cells
Present in mesophyll, contain chloroplasts to absorb lots of sunlight
Cells are boxed shaped so they can be packed close together
Thin cell walls increases rate of diffusion of co2
Large vacuole to maintain turgor pressure
Root hair cells
Present at the surface of roots
Long extensions that increase SA
Cytoplasm contains extra mitochondria to provide the energy needed for active transport
maximising water uptake
Structure and function of guard cells
Found in pairs, with a gap between them to form a stomata
When guard cells lose water they become less swollen and stoma close.
Guard cell is thicker on one side so shape does not change symmetrically. (Bend outwards) as outer wall is thicker
Structure and function of squamous epithelium
Made up of squamous epithelial cells, known as pavement epithelium.
1 cell thick
Ciliated epithelium
Made up of ciliated epithelial cells
Hair like structures called cilia that move in a rhythmic manner
Line the trachea
Examples of tissues
Squamous epithelium, ciliated epithelium
Muscle- bundle of elongated cells called muscle fibres
Xylem- made up from xylem vessels
Phloem- made up of sieve cells, companion cells, and ordinary plant cells
Differentiation of cells
In Multicellular organisms cells have to take on different roles
Cells become more specialised, adapted to their role
Production of erythrocytes and neutrophils
All blood cells are derived from stem cells in the bone marrow
Red blood cells - 120 day lifespan , due to lack or organelles (3 billion per day)
Neutrophils- 6 hour lifespan ( 1,6billion per kg per hour)
Both must be replaced constantly
Source of animal stem cells
Embryonic stem cells, toti potent until 7 days then pluripotent
Adult stem cells found in bone marrow, multi potent
Stem cell potency
Totipotent- can differentiate into any type of cell
Pluripotent - all tissue types but not whole organisms
Multipotent- range of cells within a certain type of tissue
