Unit 3 - Cellular Level Of Organization Flashcards
The cell
- basic structural and functional unit of the body
- can perform all basic life functions
Principal parts of the cell
- Cell membrane/plasma membrane/plasmalemma
- Cytoplasm (contains cytosol and organelles)
- Nucleus
Cell membrane
Boundary between the inside and outside of a cell
What is the cell membrane composed of
- Phospholipid bilayer
- Cholesterol
- Membrane proteins
- Membrane carbohydrates
- Microvilli
Phospholipid bilayer
- Phosphate head group (hydrophilic) (polar)
- FA tails (hydrophobic) (non-polar)
- Divides ICF (intracellular fluid) and ECF (extracellular fluid)
- main component is water
Cholesterol
- scattered throughout membrane
- adds stability to the cell membrane
Integral (transport) membrane proteins
- can completely pass through membrane but doesn’t always
- integrated within the membrane, therefore have a hydrophobic region
- some extend across entire membrane, and are called transmembrane proteins
Peripheral membrane proteins
- can face inside or outside of cell
- attached to either surface of integral proteins (on the periphery of the cell membrane)
Functions of membrane proteins
- enzymes
- transporters (help transport molecules in and out of cell) (ATP is required)
- channels (ATP is not required)
- receptors (tell the cell what to do)
- anchors (needs to be anchored to a certain region of the body)
- identity markers (for immune system)
Where are membrane carbohydrates found
Only on outer surfaces
What are membrane carbohydrates bound to
Proteins (glycoproteins) or lipids (glycolipids)
Function of membrane carbohydrates
- Cell recognition (spem recognizes egg)
- Anchor cells together
What is microvilli
Small projections of cell membrane
Function of microvilli
To increase surface area
Where is microvilli found
- Kidneys
- increased surface area allows more waste to be absorbed - Small intestine
- increased surface area allows us to absorb more nutrients
What makes up the fluid mosaic model of the cell membrane
- Phospholipid bilayer
- Membrane proteins
Fluid mosaic model of cell membrane
- Fluid - membrane constitutions can move around (phospholipids and some proteins)
- Mosaic - proteins dot surface, like tiles in a mosaic
What is cytoplasm
- area between the inside of the cell membrane and the outside of the nucleus
- consists of cytosol and organelles
Cytosol
- gel-like intracellular fluid
- contains water, ions, and a suspension of carbohydrates, proteins and lipids
- may contain inclusions (ex. Melanin and glycogen)
Organelles
- structures that preform a specific function and are essential for life
- can be:
1. Non-membranous- in direct contact with cytosol
2. Membranous- surrounded by membrane that isolates them from cytosol
Cytoplasm analogy
Jelly cake
- cytosol = jello
- organelles = fruit
Non-membranous organelles
- Ribosomes
- Centrosomes
- Cytoskeleton
Ribosome function
- site for protein synthesis
What do ribosomes contain
- ribosomal RNA (rRNA)
- proteins
Types of ribosomes
- Free ribosomes
- float in cytosol and make proteins that go to cytosol, mitochondria, and/or nucleus - Attached to endoplasmic reticulum (ER)
- make proteins destined for all other sites
What are Centrosomes
Organizing centres for microtubules
1. Spindle apparatus (for cell division)
2. Organizes cytoskeleton
What do Centrosomes consist of
2 components:
- a pair of centrioles
- pericentriolar matrix
Function of cytoskeleton
- all types are used for structural support (cell shape) and are formed from proteins
- important in cell movement, cell division, movement/anchoring or organelles and proteins
Types of cytoskeleton
- Microfiliaments
- Intermediate filaments
- Microtubules
What are microfilaments made of
Actin (protein)
Function of microfilaments
- muscle contraction (with myosin)
- cell locomotion
- cytokinesis (separating cytoplasm into 2 cells)
Composition of intermediate filaments
Tissue specific
- ex. Keratin (protein)
Microtubules
- hollow tubes made of tubulin (protein)
Function of microtubules
- Form:
1. centrioles
2. spindle apparatus
3. cilia (short)
4. flagella (long - move or secure organelles in place
- also found in sperm
Membranous organelles
- Mitochondria
- Endoplasmic reticulum
- Golgi apparatus/complex
- Lysosomes
- Nucleus
Mitochondria
- site of ATP synthesis
- has a double membrane (inner and outer)
What does the mitochondria contain
- DNA
- RNA
- Proteins
Endoplasmic reticulum
- membranous network throughout cytoplasm
Rough ER
- lysosomes attached
- synthesis of secretory, lysosomal and membrane proteins
Smooth ER
- lacks attached ribosomes
- continuous with rough ER
- synthesizes lipids and steroid hormones
Golgi apparatus/complex
- stacks of membrane discs
- modifies proteins (trims or adds carbs to lipids)
- sorts, packages and delivers proteins to cell membrane, lysosomes or for secretion
Golgi apparatus/complex analogy
Cellular post office
Lysosomes
- filled with digestive enzymes
- digest bacteria, viruses, worn out organelles
- clean up function
Lysosomes analogy
Lysol (cleans)
Nucleus
- largest membranous organelle
- cell control Center
- cells may have one or more nuclei
Parts of nucleus
- Nuclear envelope
- Nucleolus
- Chromosomes/chromatid
Nuclear envelope
- covers nucleus
- double membrane with nuclear pores that information passes through (inner and outer)
- connected to ER
Nucleolus
- more than 1 in some plants
- inside nucleus
- non-membranous
- dense (less light gets through) region of DNA, RNA and proteins where ribosomes are made and assembled
What do Chromosomes/chromatid contain
- DNA
- Histone proteins
(DNA is wrapped around the histone protein)
Dispersed chromosomes/chromatid
= chromatin
- DNA uncoiled and not individually visible
- in this form MOST of the time (when cell is not dividing)
Where is condensed and individually visible chromosomes/chromatid found
In dividing cells
- during mitosis and meiosis
