2.1.1 Cell Structure

Question 1

What’s the definition of resolution?

Answer 1

The (smallest distance that gives you the) ability to distinguish two points as separate.

Question 2

What’s the definition of magnification?

Answer 2

How many times larger an image appears to be compared to its actual size.

Question 3

Equation for magnification.

Answer 3

Image = Actual x Magnification

Question 4

How do light microscopes work?

Answer 4

Two lenses: objective and eyepiece
Both magnify image
(For whole cells/ tissues)

Question 5

How does a transmission electron microscope work?

Answer 5

Electromagnets used to focus beam of electrons which is transmitted through specimen.
Denser areas absorb more electrons and appear darker.
High resolution but only used on thin specimens.
B&W

Question 6

How does a scanning electron microscope work?

Answer 6

Beam of electrons scanned across specimen, electrons knocked off from specimen and gathered in cathode ray tube to form image, show surface of specimen.
CAN BE 3D
Lower resolution than TEM.
B&W

Question 7

How to calibrate an eye-piece graticule

Answer 7

Place a stage micrometer on the stage.
Line it up with the eyepiece graticule.
Each division on stage micrometer is 0.1mm.
Divide 0.1 by number of divisions on the stage micrometer, that’s what one division on eyepiece graticule equals.

Question 8

What stains can be used for light microscopes and for what specimen?

Answer 8

Methylene blue: DNA
Eosin: cytoplasm

Question 9

What’s a eukaryotic cell?

Answer 9

A cell with a membrane-bound nucleus.

Question 10

Structure of the nucleus

Answer 10

Nuclear envelope (double membrane) contains nuclear pores
Contains chromatin and nucleolus

Question 11

Function of the nucleus

Answer 11

Controls cell’s activities
Pores allow substances to move between nucleus and cytoplasm
DNA contains instructions to make proteins

Question 12

Structure of nucleolus

Answer 12

Area within nucleus comprised of proteins and RNA.

Question 13

Function of nucleolus

Answer 13

Responsible for producing ribosomes

Question 14

Structure of rough endoplasmic reticulum

Answer 14

Network of membranes enclosing flattened sacs (cisternae), connected to outer membrane of nucleus.
Surface covered in ribosomes.

Question 15

Function of rough endoplasmic reticulum

Answer 15

Folds and processes proteins made at ribosomes

Question 16

Structure of smooth endoplasmic reticulum

Answer 16

Network of membranes enclosing flattened sacs (cisternae), connected to outer membrane of nucleus.
No ribosomes.

Question 17

Function of smooth endoplasmic reticulum

Answer 17

Synthesises and processes lipids.

Question 18

Structure of Golgi apparatus

Answer 18

Compact structure of cisternae with vesicles, no ribosomes.

Question 19

Function of Golgi apparatus

Answer 19

Processes and packages proteins, makes lysosomes

Question 20

Structure of ribosomes

Answer 20

No membrane, made of RNA molecules, free-floating in cytoplasm or attached to ER

Question 21

Function of ribosomes

Answer 21

Site of protein synthesis

Question 22

Structure of mitochondria

Answer 22

Double membrane.
Inner membrane folds to form cristae.
Matrix in inside, contains enzymes for respiration.

Question 23

Function of mitochondria

Answer 23

Site of aerobic respiration, where ATP is produced.

Question 24

Structure of vesicles

Answer 24

Single membrane with fluid inside

Question 25

Function of vesicles

Answer 25

Transport materials inside the cell

Question 26

Structure of lysosomes

Answer 26

Specialised vesicles, contain hydrolytic enzymes

Question 27

Function of lysosomes

Answer 27

Responsible for breaking down waste materials in cells, role in immune system: breaking down pathogens

Question 28

Structure of chloroplasts

Answer 28

Double membrane Stroma is the fluid enclosed Internal network of membranes, form thylakoids (stacked together called grana) Grana linked by lamellae

Question 29

Function of chloroplasts

Answer 29

Site of photosynthesis

Question 30

Structure of plasma membrane

Answer 30

Made of lipids and protein

Question 31

Function of plasma membrane

Answer 31

Regulates movement of substances in/out of cell Receptor molecules to respond to hormones etc

Question 32

Structure of centrioles

Answer 32

Component of cytoskeleton Made of microtubules in a small hollow cylinder Two form the centrosome

Question 33

Function of centrioles

Answer 33

Assembly and organisation of spindle fibres during cell division

Question 34

Structure of cell wall

Answer 34

In plants: made of cellulose, complex carbohydrate

Question 35

Function of cell wall

Answer 35

Supports plant cells Freely permeable, substances can pass in/out of cell

Question 36

Structure of flagella

Answer 36

Whip-like extensions, longer than cilia Surrounded by plasma membrane 2 microtubules in centre, 9 pairs around edge

Question 37

Function of flagella

Answer 37

Microtubules contract so flagellum move, propel the cell forward

Question 38

Structure of cilia

Answer 38

Hair-like extensions Outer membrane, 9 pairs of microtubules in a ring and 2 in the middles

Question 39

Function of cilia

Answer 39

Microtubules allow cilia to move substances along cell surface

Question 40

Describe the process of protein production and secretion within cells

Answer 40

Proteins synthesised on ribosomes bound to ER Pass into cisternae and packaged into transport vesicles Vesicles with synthesised protein move towards Golgi apparatus via transport function of cytoskeleton Vesicles fuse with cis face of Golgi and enter Proteins modified before leaving Golgi in vesicles from trans face Secretory vesicles carry proteins that are to be released from cell Vesicles fuse with cell-surface membrane and release contents by exocytosis

Question 41

Explain importance of the cytoskeleton

Answer 41

Network of fibres necessary for shape and stability of a cell holds organelles in place, controls cell movement and movement of organelles in cells Three components: Microfilaments are responsible for cell movement and cell contraction during cytokinesis Microtubules are tubes that are used to determine shape of a cell, track movement of organelles around the cell Intermediate fibres give mechanical strength to cells

Question 42

Differences between nucleus in pro and eukaryotic cells

Answer 42

Prokaryotic cells don’t have a nucleus, eukaryotic cells do

Question 43

Differences between DNA in pro and eukaryotic cells

Answer 43

DNA in prokaryotic cells is circular, DNA in eukaryotic cells is linear

Question 44

Differences between DNA organisation in pro and eukaryotic cells

Answer 44

Proteins fold and condense DNA in prokaryotic cells, associated with histones in eukaryotic cells

Question 45

Differences between extra chromosomal DNA in pro and eukaryotic cells

Answer 45

Circular DNA (plasmids) in prokaryotic, only present in certain organelles (mitochondria, chloroplasts) in eukaryotic

Question 46

Differences between organelles in pro and eukaryotic cells

Answer 46

Only non membrane bound in prokaryotic, both non and membrane bound in eukaryotic

Question 47

Differences between cell wall in pro and eukaryotic cells

Answer 47

Peptidoglycan in prokaryotic, chitin/cellulose or not present in eukaryotic (fungi,plants,animals)

Question 48

Differences between ribosomes in pro and eukaryotic cells

Answer 48

Smaller (70S) in prokaryotic, larger (80S) in eukaryotic

Question 49

Differences between cytoskeleton in pro and eukaryotic cells

Answer 49

Present in both, more complex in eukaryotic

Question 50

Differences between reproduction in pro and eukaryotic cells

Answer 50

Binary fission in prokaryotic, asexual/sexual in eukaryotic

Question 51

Differences between cell type in pro and eukaryotic cells

Answer 51

Only unicellular in prokaryotic, both uni and multicellular in eukaryotic

Question 52

Differences between cell surface membrane in pro and eukaryotic cells

Answer 52

Present in both

Question 53

Order of magnification of microscopes

Answer 53

Transmission electron microscope > scanning electron micoscope > light microscope

Question 54

Order of resolution of microscopes

Answer 54

Transmission electron microscope > scanning electron microscope > light microscope