IB Biology Topic 1

1. All living things are composed of cells 2.The Cell in the fundamental unit of life

2. Cells only arise from pre-existing cells

Long Cells, (300 mm), multiple nuclei, questions cell theory

challenges idea that cell is a single unit, multi-nucleated, and continuous cytoplasm. Cell walls composed of Chitin

challenges that notion that cells must be small, and simple in structure. Size of 5-100mm and complex in form.

Living things can respond to and interact with the environment

The maintenance and regulation of internal cell conditions, e.g. water and pH

Living things can grow/change

removal of metabolic waste

living things produce offspring, sexually or asexually

feeding by either the synthesis of organic molecules (e.g. photosynthesis) or the absorption of organic matter

A larger SA:Vol ratio can mean that a cell can act more efficiently. For every unit of volume that requires nutrients or produces waste. There is more membrane to serve it

Cells divide, They use membranes to carry out processes, organs will fold up to maximize the ratio

a function of mass/volume

when things are added more properties arise

All specialized cell and the organs constructed are from differentiation

unspecialized cells that can differentiate into many cell types - Embryonic - Cord Blood - Adult (bone marrow)

Can differentiate into any cell

Can differentiate into many cells

can differentiate into a few closely related cells

Can regenerate,but only into associated cell type

A recessive condition for the eyes, stem cells are treated to become retinal cells. Cells attach to the retina and improves central vision

Hematopoietic Stem Cells (HSCs) are harvested from bone marrow, peripheral blood or umbilical cord blood Chemotherapy and radiotherapy used to destroy the diseased white blood cells New white blood cells need to be replaced with healthy cells. HSCs are transplanted back into the bone marrow HSCs differentiate to form new healthy white blood cells

approximately 0.5 μm

Asexually through binary fission.

1. Two loops attach to membrane

2. Elongation and pinches off

3. Two identical cells

Their DNA is not enclosed in within a membrane and forms on circular Chromosome Their DNA is free; it is not attached to proteins They lack membrane-bound organelles. Ribosomes are complex structures within the plasma membrane, but they have no exterior membrane Their cell wall is made up of a compound called peptidoglycan They usually divide by binary fission, a simple form of cell division They are characteristically small in size, usually between 1 and 10 µm

1 micrometer

Generally Spherical with a double membrane. Pores and holes are present. Contains Chromosomes.

Has a smooth outer membrane. Folds are cristae. Variable Shape. Site of ATP production by aerobic energy

80S ribosomes. No membrane, appear as dark granules in cytoplasm. Synthesizes proteins to function in cytoplasm.

Consists of Flattened membrane sacs (cisternae). Located near nucleus. 80S ribosomes are attached to outside of cisternae rEr synthesizes transported proteins by vesicles to golgi for modification

Contains cisternae No attached ribosomes often sited close to plasma membrane shorter and more curved than the rER. modifies proteins from the rER , the repackaged in vesicles

A single membrane with fluid Small Transport Materials inside cell

Spherical with single membrane Golgi vesicles Digestive enzymes from breakdown of: food unwanted organelles cell itself High concentration of enzymes, cause this to stain heavily and hence appear dark on micrographs

Single Membrane with fluid inside Plant cells vacuoles are large and permanent often occupying cell volume In animals vacuoles are smaller and used for various other reasons

Thin projection from cell surface. Contain microtubules Used to move cell

Thin projections from cell surface Contain Microtubules Used to either move cell or the move the fluids next to the cell

Small Cylindrical fibers Have a variety of functions, part of flagella. Cell division

Nine triple miroctubules manly found in animal cells not vascular plants of fungi

Many, but not all plant cells contain chloroplasts Inside are thylakoids Flattened membrane Shape is variable,but usually ovoid Site of photosynthesis and hence where glucose is produced Starch grains may be present if photosynthesis is quick

extracellular secreted by plants permeable Strong Hard to Digest

70S

is all the structures of a biological specimen that are at least 0.1nm in their smallest dimension

Hydrophillic Head Hydrophobic Tail

Heads are wet and tails are dry

is one way that the tails are removed from water

Permanently embedded many go all the way through and are polytopic, some are monotopic

Many Surfaces

Temporary association and are monotopic

sugar chain attached. Cell recognition by immune system as hormone receptors

Transport

Receptors

Anchorage

Cell Recognition

Intercellular Joinings

Enzymatic Activity

Protein Channels and Pumps

Peptide based hormones

Cytoskeleton attachments and extracellular matrix

MHC proteins and antigens

Tight Junctions and plasmodesmata

Metabolic pathways

Makes phospholipids pack more tightly and regulates fluidity and flexibility of memebrane.

restricts movement. Disrupts regular packing of the hydrocarbon tails. This increases flexibility

Membrane proteins are varied in size and globular. Such proteins are unable to form continuous layers

A protein-lipid sandwich. Proteins coat surface. Do not permeate the bylayer.

The fracture occurs along lines of weakness, including the center of membranes. The fracture reveals an irregular rough surface inside the phospholipid bilayer

Some cannot pass through and different forces

Net movement of particles from high to low concetration.

When a cell is submurged water molecules pass through the cell from low to high solute concentration.

Higher concentration of solutes

When the concentrations are equal on both sides

lower concentration of solutes

proteins recognize a particular molecule and help it move across the membrane.