Unit 1

Question 1

Features that define a cell

Answer 1

1) membrane enclosed autonomous living unit
2) unit can maintain a stable internal environment with molecules and ions that differ from the external environment
3) capable of storing DNA and guiding the synthesis of RNA and protein
4) can convert energy from one form to another (ie carrying out metabolism to make ATP)
5) can grow and reproduce

Question 2

Are viruses cells?

Answer 2

No - they are parasites of living cells and depend on the host cell for raw materials and energy for nucleic acid synthesis, protein synthesis, processing and transport, and other things that allows it to multiple and spread

Question 3

Organelles

Answer 3

different structures within a living cell that perform specialized functions

Question 4

Why are organelles important?

Answer 4

1) carry out unique function in the cell
2) provide optimal local environment for metabolic reactions and other functions
3) allow high local concentration of molecules, ions, etc. at a certain cellular location to be achieved
4) control passage of materials

Question 5

Do all cells have organelles? Compare eukaryotic and prokaryotic cells

Answer 5

Yes

Euks: nucleus and other membrane-enclosed organelles/compartments

Proks: do not have membrane-enclosed organelles

Question 6

Which organelles are membrane-enclosed?

Answer 6

membrane:
Nuc, mito, chloro, lysosome, peroxisome, ER, golgi

no membrane:
ribosomes, filaments, microtubules

Question 7

What is an organism?

Answer 7

has/can develop the ability to act/function independently. They are capable of:

metabolism/homeostasis
growth and reproduction
responses to the environment

Question 8

Cytosol

Answer 8

everything in the plasma membrane minus the organelles

Question 9

Cytoplasm

Answer 9

everything within the plasma membrane

Question 10

Cell theory

Answer 10

1) all living organisms are made of cells
2) cells are the basic building units of life
3) new cells arise by division of existing cells

Question 11

Size of nucleus

Answer 11

approx. 6-10 micrometers

Question 12

Magnification

Answer 12

expanding something in apparent size. It is the ratio of the size of an image to the size of the object

Question 13

Resolution

Answer 13

defined as the closest spacing of two point which can be distinguished as separate entities. Major factor that determines it is the wavelength of the beam (light, electrons) used for imaging

Question 14

Types of light microscopy and resolution limit. What is it used to visualize?

Answer 14

transmitted light microscopy (bright field microcopy)

emitted light microscopy (fluorescence microscopy)

resolution limit is 0.2 microm (200nm)

used to visualize whole tissues, fixed, often sectioned and stained (not alive)
colour
live cells

Question 15

Types of electron microscopy

Answer 15

transmission electron microscopy

scanning electron microscopy

Question 16

Limitation of light microscopy

Answer 16

live cells lack contrast

cells have to be “fixed”, thus killing them

Question 17

Emitted light microscopy - fluorescence

Answer 17

Fluorescently labelled molecules/structures for localization in cells

Can use
Direct staining - using fluorochromes
Indirect staining - using fluorochrome-linked antibodies
Tagging of protein with GFP

Question 18

Indirect staining - immunofluorescence. Name 3 limitations

Answer 18

Localizes proteins of interest using primary antibodies. Secondary antibodies covalently linked to a fluorochrome recognizes the primary antibody

Takes too long
May have issues
Cannot do it for live cells (not sure)

Question 19

Direct staining

Answer 19

Gene for green fluorescent protein (GFP) can be fused with the gene of interest so when the gene is expressed, it’ll produce a protein with a GFP tag on it

Question 20

Advantages/disadvantages of light microscopy

Answer 20

Adv:
Colour
Use live, whole cells
Track cells
Cheap and easy

Disadv:
Cannot see smaller structures
Lower resolution

Question 21

When do you use transmitted or fluorescence light microscopy?

Answer 21

Transmitted:
Don’t need colour or use visible dyes
Visualize whole tissues
Cheap and easy to use

Fluorescence:
See the localization of specific protein
Need to see colour
Tracking proteins or organelles

Question 22

Electron microscopy features

Answer 22

Res limit: 0.2 nm
Images are black and white
Uses electron beam (short wavelength) to illuminate sample
Tissues are fixed (dead)

Question 23

TEM advantages and disadvantages

Answer 23

Adv:
High res such that details of cytoplasm can be seen

Disadv:
Cells are fixed
Complex specimen preparation
Difficult to know 3D shape of structure
Only shows a single slice (cross section)

Question 24

Scanning electron microscopy advantages and disadvantages

Answer 24

Adv:
Can view surfaces (images appear 3D

Disadv:
Cells must be fixed