Week 4 - A Tour Of The Cell

Question 1

Unified cell theory

Answer 1

All living things made of cells

Question 2

Two types of cells

Answer 2

Prokaryotic and Eukaryotic

“Pro”-before, early, pre
“Kary”-nucleus (carries DNA)

Question 3

Prokaryotic cells

Answer 3

Lack membrane bound organelles; Have a nucleoid instead of a nucleus

Domains Archaea and Bacteria are prokaryotic

Question 4

Eukaryotic cells

Answer 4

Have membrane bound organelles and true nucleus (houses the genetic material)

“Eu”-good, true
“Kary”-carries DNA

Question 5

Three domains of biology

Answer 5

Eukarya - plants, animals, fungi
Archaea
Bacteria

Question 6

Organelle

Answer 6

Mini organ or structure within a cell

Organelle - “organs” of the “cell” –> organelle

Question 7

Nucleus

Answer 7

Center of cell, holds genetic material and directs mfg of proteins.

Three main parts:

1) nuclear envelope / membrane
2) nucleolus (center of nucleus, makes ribosomes)
3) chromatin (houses chromosomes, genetic material, DNA)

Question 8

Cytoplasm

Answer 8

Everything inside the cell between PM and nucleus including:

Cytosol, Organelles, Proteins, Chemicals

Question 9

Cytosol

Answer 9

Fluid within the cell. Water based, gel-like substance. Part of the cytoplasm.

Question 10

Nuclear envelope

Answer 10

Aka nuclear membrane

Functions: encases the nucleus; controls what comes in and out

Question 11

Chromatin

Answer 11

Mass of DNA and the proteins that give it structure/organization

Question 12

Chromosome

Answer 12

The long, discrete strands of DNA; smallest units of DNA

Question 13

Nucleolus

Answer 13

Makes ribosomes; center of nucleus

Question 14

Ribosomes

Answer 14

Organelle that makes proteins (protein synthesis)

Receive instructions from RNA

comprised of a small and large subunit that attach to mRNA in protein synthesis

Two types:
FREE RIBOSOMES - float around freely in the cytoplasm
BOUND RIBOSOMES - bound to the ER or nuclear envelope

Question 15

Lysosomes

Answer 15

Organelles that break things down via hydrolysis using Digestive enzymes

Can break down food or damaged cell materials; Made by the Golgi apparatus/complex

Question 16

Peroxisomes

Answer 16

Facilitate oxidation rxns by providing the needed enzymes

Break down toxic materials (like alcohol —> lots of peroxisomes in the liver!) and FAs

Question 17

Why is it important for enzyme containing organelles like Lysosomes and Peroxisomes to be membrane-bound?

Answer 17

So the cell doesn’t digest itself!

Question 18

Vacuoles

Answer 18

Large compartments with specific fxns in different organisms

Examples:
Food vacuoles - sacs of nutrients taken in to be digested by lysosomes
Contractile vacuoles - pump water out of cell in freshwater unicellular eukaryotes IOT maintain proper water/ion concentration
Central vacuole - common in mature plant cells; storage and cell growth

Question 19

Endoplasmic reticulum - 2 types

Answer 19

Smooth ER - no ribosomes
Rough ER - embedded ribosomes on outer surface

All ER is continuous w/ nuclear membrane; Internal area is separate from cytosol and called ER lumen

Question 20

Smooth ER functions

Answer 20

Makes lipids (incl. steroids) and carbs
Detox of drugs/poisons
Stores Ca ions

Question 21

Rough ER functions

Answer 21

Creates proteins (ribosomes) to secrete from cell
Makes membrane phospholipids for itself and rest of cell

Question 22

Golgi apparatus/complex

Answer 22

Receives sorts and transports proteins - post office of the cell

Cis face receives vesicles; trans face sends them off (for transport)

May modify product (e.g. protein) before sending off

Receives transport vesicles from ER (e.g. containing proteins)

Question 23

Endosymbiont Theory

Answer 23

explains origins of mitochondria and chloroplasts; Idea that they were once free but got absorbed by a eukaryote ancestor

mitochondria and chloroplasts: 
Have their own DNA 
Replicate their DNA autonomously
Have their own ribosomes 
Approx same size as a bacterial cell

Question 24

Mitochondria

Answer 24

perform cellular respiration; use O2 (aerobic) to obtain ATP (energy) from food to power cell.

Question 25

Chloroplasts

Answer 25

green in color due to chlorophyll pigment (makes plants green); sites of PHOTOSYNTHESIS - Absorption of sun and use of energy to make sugar

Question 26

Chlorophyll

Answer 26

Bright green pigment that helps capture light energy for photosynthesis

Question 27

Cytoskeleton

Answer 27

fiber network that physically organizes structures and activities of the cell

Question 28

Three fiber types comprising cytoskeleton

Answer 28

Microfilaments - made of actin; interact w/ myosin to create mvmt; animals use for mvmt, plants use to circulate cytoplasm

Intermediate filaments - immobile, strong, and permanent; e.g. hair

Microtubules - hollow rods; shape/support the cell; aid in movement; give shape and resist compression

Question 29

Cilia

Answer 29

made up of microtubules; participate in movement mainly moving fluid; vast in qty per cell

Question 30

Flagella

Answer 30

create mvmt of a whole cell (e.g. sperm); 1 to 4 flagella per cell

Question 31

Centrosome

Answer 31

organizing center of the microtubules; also functions in cell division

Question 32

Cell wall

Answer 32

Found ONLY in plants and fungi; hard structure (external) which protects and supports the cell; made of cellulose and chitin

Question 33

Plasmodesmata

Answer 33

small channels in cell walls of plants

Question 34

PM Plasma Membrane

Answer 34

Phospholipid bilayer; separates internal cellular environment from external