chap 6 Flashcards
What is a specialised cell?
a Cell that has Differentiated to carry out its very Specific Function.
Specialised cell enters G0
What is a Tissue?
Tissue is a collection of differentiated cells that work together to carry out a specialised function.
Each tissue is adapted for a particular function in an organsim.
4 main categories of tissues in animals?
Nervous tissue - adapted to support transmission of electrical impulses.
Epithelial tissue - adapted to cover body surfaces, internal or external.
Muscle tissue - adapted to contract.
Connective tissue - adapted to hold other tissues together, or adapted as a transport medium.
Erythrocytes
Flattened biconcave shape = increases SA:V ratio
No Nuclei and few organelles = more space for haemoglobin (carries O)
Flexible = can squeeze through capillaries.
Neutrophils (type of WBC)
Multi-lobed Nucleus = easier to squeeze through small gaps to get to site of infection (phagocytic leukocytes)
Granular cytoplasm; contains many lysosomes that contain enzymes used to attack pathogens
Sperm Cells
Haploid = produce diploid zygote upon fertilisating egg
Flagellum = tail so is capable of movement
Many Mitochondria = provide energy for movement
Acrosome on head = contains digestive enzymes, released to breakdown protective layers around ovum to allow sperm to penetrate, leading to fertilisation.
Palisade Cells
present in the Mesophyll
Chloroplasts to absorb light for photosynthesis can move within cytoplasm to absorb more light
Rectangular box Shaped = can be Closely Packed to form a continuous layer.
Thin Walls = faster rate of Diffusion of CO2
Large Vaculole = maintain Turgor pressure.
Root Hair Cells
present at surface of roots near Growing Tips
Long Extentions; Root Hairs = increase SA of cell to maximise uptake of water from soil.
Guard Cells (in pairs)
On leaf Surface, form opening called Stomata
Enable gas exchange CO2 & O2 out.
When guard cells Lose water and become less swolen = Flacid; guard cell changes shape= stomata Close; preventing further water loss
When guard cells gain water and become swollen = turgid, stomata open
Squamous Epithelium (tissue)
Made of Squamous Epithilial Cells
Flat
Very Thin - as made of flat cells & only one cell thick
Present where rapid diffusion is necessary; thin so short diffusion distance.
e.g. forms lining of lungs, allowing rapid gas exchane of O2 into blood.
Cilliated Epithilum (tissue)
Made of Ciliated Epithilial Cells
Cilia/hair-like structures on apical surafece - beat/move in rhythmic matter to waft substances.
e.g. lines trachea, sweping mucus up & out of lungs.
Cartillage (tissue)
Connective tissue
Composed of Chondrocyte Cells embedded in an extracellular matrix
In outer ear, nose, and at end of/between bones - prevents ends of bones rubbing causing damge.
Firm & Flexible
Contains Elastin and Collagen.
Muscle
Skeletal, Smooth, Cardiac muscles.
Skeletal Muscles (attached to bone) contain myofibrils which contain contractile proteins (myosin&actin)
Made of several individual muscle fibres separated by connective tissue.
Main types of tissue in Plants
Vascular Tissue - adapted for transport of water and nutrients
Epidermal Tissue - adapted to cover plant surfaces
Epidermis (plant tissue)
A Single Layer of Closely Packed cells, covering the surface of plants, usually Covered by a Waxy Waterproof Cuticle = reduce water loss.
Stomata present = for gas exchange
Xylem Tissue
Composed of Vessel Elements - Elongated Dead Cells; walls Strengthened by Lignin (waterproof)
provide Structural Support for plants
Responsible for water & mineral transport (vascular).
Phloem Tissue
Composed of collumns of Sieve Tube Cells, separated by Sieve Plates (Perforated walls)
Responsible for transport of organic nutrients (sucrose) from source to sink in plants (Vascular).
What is an Organ?
A collection of tissues adapted to perform a particular function in the organism.
e.g. mamalian heart is adapted for pumping blood, made of cardiac muscle tissue and connective tissue.
What is an Organ System?
Number of Organs working together in a coordinated mannar to carry out a major function.
e.g. Cardiovascular system (animal) - moves blood around body to provide an effective transport system for the substances it carries.
What are Stem Cells?
Undifferentiated cells, not adapted to any particular function and have the potential to differentiate and become one of the range of specialised cell types in the organism.
Differentiation
Process of cell Becoming Specialised.
Involves expression of some genes but not others in the cell’s genome.
Stem Cells
Undifferentiated cells that have potential to differentiatye into a specialised cell.
Able to undergo cell division over & over
Source of new cells, necessary for growth, development & repair.
Why must Stem Cells be Strictly controlled?
They must divide fast enough to repair tissue efficiently
If divide uncontrolled then masses called tumors form, which can lead to developemnt of cancer.
What is Stem Cell Potency?
A Stem Cell’s Ability to differentiate into different cell types.
Greater number of cell types = Greater Potency
