Topic 3: Cellular level of Organization, part 2 Flashcards
Cell
Basic structural and functional unit of the body
can perform all basic life functions
Who is Robert Hooke?
1st discovered cells
-> cork cells (dead cells)
What is the cell membrane composed of?
a) Phospholipid bilayer
b) Cholesterol
c) Membrane proteins
d) Membrane carbohydrates
Phospholipid bilayer
i. phosphate head group (hydrophilic)
ii. FA tails (hydrophobic)
iii. divides ICF + ECF
* barrier, selective to what can enter or exit
Intracellular Fluid (ICF)
inside cell
Extracellular Fluid (ECF
outside the cell
Cholesterol
i. scattered throughout membrane
ii. adds stability to the cell membrane
at high temp= membrane will be moving lots breaking bonds melting so you want it to be less fluid
at low temps it will be moving less, so you want it to be more fluid
What are the 2 types of membrane proteins?
Integral
peripheral
Integral proteins
integrated within the membrane, therefore have a
hydrophobic region
¦ some extend across entire membrane, and are called
transmembrane proteins
peripheral proteins
¦ attached to either surface of integral proteins
i.e. on the periphery of the cell membrane
Membrane Proteins - Functions:
enzymes • transporters • channels • receptors- hormones • anchors • identity markers (for immune system)
Membrane carbohydrates
only on outer surface; not in contact with ICF only ECF
• bound to proteins (glycoproteins) or lipids (glycolipids)
List the functions of membrane carbs:
i. cell recognition e.g. sperm recognize egg cell
ii. anchor cells together
Microvilli
- small projections of cell membrane
- function is to increase surface area
- best seen on cells of the small intestine and kidney
- Not all cells have these
Fluid Mosaic Model
fluid - membrane constituents can move around (phospholipids and some proteins)
mosaic – proteins dot surface like tiles in a mosaic
Cytoplasm
AREA between the inside of the cell membrane and the outside of the nucleus.
LIKE CANADA IS AN AREA
What are the 2 divisions of the cytoplasm?
a) Cytosol
b) organelles
Cytosol =
gel-like intracellular fluid contains water, ions (e.g. K+, Na+ ) and a suspension of carbohydrates, proteins, and lipids
may contain inclusions e.g. melanin (pigment), glycogen (stored glucose)
Organelles
structures that perform a specific function and are essential for life
i. non-membranous
in direct contact with cytosol
ii. membranous
surrounded by membrane that isolates them from the cytosol
List the non -membranous organelles
a) Ribosomes
b) Centrosomes
c) Cytoskeleton
Ribosomes
sites for protein synthesis
contain ribosomal RNA (rRNA) + proteins
may be:
→ free in cytosol - make proteins destined for cytosol, mitochondria, nucleus
→ attached to endoplasmic reticulum (ER) - make proteins destined for all other sites
Centrosomes
Consist of 2 components: a pair of centrioles and the pericentriolar matrix
Organizing centres for microtubules
• spindle apparatus (for cell division)
• organizes cytoskeleton
Cytoskeleton
ALL types support cell shape and are formed from PROTEINS
important in cell movement, cell division, movement/anchoring of
organelles + proteins (e.g. receptors, enzymes)
What are the 3 types of cytoskeleton?
a) microfilaments
b) microtubules
c) intermediate filaments
microfilaments
made of actin
Functions: • muscle contraction (with myosin) • cell locomotion • maintenance of cell shape and projections (e.g. microvilli) • cytokinesis
intermediate filaments
composition is tissue specific e.g. keratin
Function:
• support the cytoplasm (scaffolding for the cell)
microtubules
hollow tubes made of tubulin
Function: • form: 1. centrioles 2. spindle apparatus 3. cilia (short) 4. flagella (long) • structural • move or secure organelles in place
cilia
mulitple
hair like projections (in resp, tract push mucous out)
short
flagella
long
1 or 2
sperm only have this within human body
List the Membranous organelles
a) Mitochondria
b) Endoplasmic reticulum (ER)
c) Golgi Apparatus/Complex
d) Lysosomes
e) Nucleus
Mitochondria
site of ATP synthesis
contains own DNA, RNA, + proteins
have a double membrane (outer and inner, 4 phospholipids, 2 bilayers)
Who do you inherit your mitochondrial DNA from?
Mother
Endoplasmic reticulum (ER)
membranous network throughout cytoplasm
2 types:
Rough ER (RER)
- ribosomes attached - synthesis of secretory, lysosomal and membrane proteins
• Smooth ER (SER)
- lacks attached ribosomes
- continuous with RER
- synthesizes lipids + steroid hormones
Golgi Apparatus/Complex
stacks of membrane discs
modifies proteins (e.g. trims or adds carbs and lipids), sorts, packages, and delivers them to cell membrane, lysosomes, or for secretion
(cellular post office)
- like post office
Lysosomes
filled with digestive enzymes
digest bacteria, viruses, worn-out organelles
(clean up function)
- part of immune function
Nucleus
largest membranous organelle
cell control centre
* dictating kinds and amount of proteins
cells may have 1 or more nuclei (mulit nucleated, RBC; anucleated, no nucleus)
List the parts of the nucleus
a) nuclear envelope
b) nucleolus (>1 in some plants)
c) chromosomes/chromatids
nuclear envelope
double membrane with nuclear pores (2 bilayers), selective don’t want to damage the DNA
connected to ER
nucleolus
non-membranous; easily seen in microscope
dense (less light gets through) region of DNA, RNA, + proteins
where ribosomes are made and assembled
chromosomes/chromatids
contain DNA + histone proteins
can be:
• dispersed = Chromatin
- DNA uncoiled + not individually visible
- in this form MOST of the time (when cell is not dividing, so that we can read it and make DNA-> MRNA
• condensed + individually visible
- found in dividing cells (during mitosis/meiosis)
Can peripheral proteins be on either surface, in contact with ECF and ICF?
Yes
Keratin is found in which part of the cytoskeleton?
IF
