Cellular level of organization

Question 1

cell

Answer 1

basic structural and functional unit of the body

-can perform all basic life functions

Question 2

Principal parts of the cell

Answer 2

• cell membrane/ plasma membrane/plasmalemma
• cytoplasm
• non-membranous organelles
• membranous organelles
• nucleus

Question 3

what is the cell membrane composed of?

Answer 3

a) phosopholipid bilayer
-phosphate head group
-FA tails
-divides ICF + ECF
b) cholesterol
-scattered throughout membrane
-adds stability to the cell membrane
c) membrane proteins
two types: integral and peripheral
d) membrane carbohydrates
-only on outer surface
-bound to proteins (glycoproteins) or lipids (glycolipids)
-functions: cell recognition (egg and sperm)
and anchor cells together
e) microvilli
-small projections of cell membrane
-function is to increase surface area
-best seen on cells of the small intestine and kidney

Question 4

integral proteins

Answer 4

within the membrane therefore have a hydrophobic region

-some extend across entire membrane = transmembrane

Question 5

peripheral proteins

Answer 5

attached to either surface of integral proteins

Question 6

membrane protein functions (6)

Answer 6

enzymes
transporters
channels
receptors
anchors 
identity markers (for immune sys)

Question 7

fluid mosaic model of the cell membrane

Answer 7

phospholipids and membrane proteins

• fluid- membrane constituents can move around
• mosaic- proteins dot surface like tiles in a mosaic

Question 8

Cytoplasm

Answer 8

area b/w the inside of the cell membrane and the outside of the nucleus
-2 divisions:
cytosol and organelles

Question 9

cytosol

Answer 9

gel like intracellular fluid
-contains water, ion and suspension of carbohydrates, proteins and lipids 
-many contain inclusions
eg. melanin (pigment
glycogen (stored glucose)

Question 10

organelles

Answer 10

structures that perform a specific function and are essential for life

• non-membranous is in direct contact with cytosol
• membranous are surround by membrane that isolates them from the cytosol

Question 11

non membranous organelles

Answer 11

• ribosomes
• centrosomes
• cytoskeleton

Question 12

ribosomes

Answer 12

• sites for protein synthesis
• contain ribosomal RNA (rRNA) + proteins
• may be free in cytosol- make proteins diestine for cytosol, mitochondria, nucleus
• attached to ER- Make proteins destined for all other sites

Question 13

centrosomes

Answer 13

dense area of cytoplasm, usually contains 2 centrioles (function uncertain- some cells lack them)

• organizes microtubules to form spindle apparatus (for cell division)
• organizes cytoskeleton

Question 14

cytoskeleton

Answer 14

determines cell shape (Cell support) formed from proteins

-functions- important in cell movement, cell division, movement/anchoring of organelles + proteins

Question 15

types of cytoskeletons

Answer 15

microfilaments
intermediate filaments
microtubules

Question 16

microfilaments

Answer 16

made of actin
- function
muscles contraction with myosin
cell locomotion
maintenance of cell shape and projections 
cytokinesis

Question 17

intermediate filaments

Answer 17

composition is tissues specific

function: support the cytoplasm ( scaffolding for the cell)

Question 18

microtubules

Answer 18

hollow tubes made of tubulin
function: form centriols, spindle apparaus, cilia (short), flagella (long)
-structural
0move or secure organelles in place

Question 19

membranous organelles

Answer 19

mitochondria
ER
Golgi apparatus
lysosomes

Question 20

mitochondria

Answer 20

• site of ATP synthesis
• contains own DNA, RNA, + proteins
• have double membrane

Question 21

ER

Answer 21

membranes network throughout cytoplasm

• RER- ribosomes attached- synthesis of secretory, lysosomal and membrane proteins
• SER- lacks attacked ribosomes, continuous with RER and synthesizes lipids and steroid hormones

Question 22

Golgi apparatus

Answer 22

stack of membrane discs
-modifies (eg. trims or adds CHO groups), sorts, packages and delivers proteins/ lipids to cell membrane, lysosomes, or for secretion (cellular post office)

Question 23

lysosomes

Answer 23

filled with digestive enzymes

-digest bacteria, viruses worn out organelles (clean up function)

Question 24

nucleus

Answer 24

largest membranous organelle
-cell control centre
-cells may have 1 or more nuclei
3 parts:
nuclear envelope
nucleolus
chromosomes/ chromatids

Question 25

nuclear envelope

Answer 25

double membrane with nuclear pores

connected to ER

Question 26

nucleolus

Answer 26

> 1 in some plants

• non membraneous
• dense (less light gets through) region of DNA, RNA and proteins where ribosome’s are made and assembled

Question 27

chromosomes/chromatids

Answer 27

contain DNA and histone proteins

• can be dispersed=chromatin
• DNA uncoiled and not individually visible
• in this form most of the time ( when cell is not dividing)
• can be condensed and individually visible
• found in dividing cells (during mitosis / meiosis)