Chapter 4

Question 1

What was the statement in the very first published cell theory?

Answer 1

“All living things are composed of living cells”

Question 2

3 principles of complete cell theory

Answer 2

• all living things are made of cells
• a cell is the smallest unit in a living thing
• all cells come from other cells

Question 3

Magnification

Answer 3

The increase in apparent size of an object. Said using #x

Ex. Saying we viewed something at 100x means that the objects was magnified at 100x its original size

Question 4

Resolution

Answer 4

A measure of clarity of an image.

The ability of an optical instrument to show to nearby objects as separate.

Question 5

Light microscopes

Answer 5

Can effectively magnify objects at about 1000x.

Typically used for live specimens in order to see movement.

Cannot achieve great resolution on these microscopes.

Question 6

Electron microscopes

Answer 6

Focus a beam of electrons through a specimen (transmission electron microscopy), or onto its surface (scanning electron microscopy).

The beam of electrons excites electrons on the surface of the sample, and these electrons are detected by a device that translates their pattern into an image

Question 7

2 principle types of cells

Answer 7

Prokaryotic cell: archaea and bacteria
- no membrane bound organelles
- 1/10 size of eukaryotic cell
- reproduce via binary fission
- capsule exterior helps evade from antibiotics/ being consumed by predators.

Eukaryotic cell: plants and animals
- membrane bound organelles
- nucleus holding DNA/RNA

Question 8

Nucleus

Answer 8

Control center of the cell, holding the DNA. The DNA is coded with instructions which know how to produce proteins, hormones, and other things facilitating the cell.

Question 9

Nuclear envelope / membrane

Answer 9

A tightly attached double-layered membrane surrounding the nucleus. It helps protect the DNA inside.

Question 10

Nuclear pores

Answer 10

Small channels along the nuclear envelope that allow certain molecules to go in or out of the nucleus. (Semipermeable)

Question 11

Nucleoplasm

Answer 11

A jelly like matrix that all other materials in the nucleus “float” in.

Question 12

Chromatin

Answer 12

The material in the nucleus which composes chromosomes. It is composed of DNA, RNA, and the protein histone

Question 13

Nucleolus

Answer 13

(Note: “nucleoli” = plural)

Dark stained circle-like structures in the nucleus. They are full of RNA.

Function to produce ribosomes.

Question 14

Ribosomes

Answer 14

Protein making machines.

Can either be floating around in the cell (which means the proteins will be used for cellular purpose)
Or
Attached the the rough ER (which means the proteins will be exported for use outside of the cell)

Question 15

Rough endoplasmic reticulum

Answer 15

Contains many ribosomes on the outside of its surface. It will help in the protein synthesis of ribosomes and export the proteins to the Golgi apparatus. It will also make more membrane.

(Shares the nuclear envelope membrane with the nucleus)

Question 16

Smooth endoplasmic reticulum

Answer 16

Lacks ribosomes.

Is involved in the synthesis of steroid hormones and lipids. Can also detoxify drugs, alcohol…etc (in liver cells)

(Shares the nuclear envelope membrane with the nucleus)

Question 17

Golgi apparatus

Answer 17

Contain several flattened “sacs” called cisternae

Receive proteins from the rough ER and modifies them if needed. Then it will ship it through one of its transport vesicles.

Question 18

Lysosomes

Answer 18

Made by the rough ER, processed in the GA.

Contain digestive enzymes that are able to digest toxic material lying within a cell, or digest old cellular debris that isn’t useful anymore.

Question 19

Vacuoles

Answer 19

In animals:
Water containing vesicles that help eliminate excess water.

In plants:
Have digestive functions or contain poisons to protect the plant

Question 20

Peroxisomes

Answer 20

Will break down fatty acids. And in the liver it will detoxify alcohol into hydrogen peroxide, which enzymes will further convert into water.

Question 21

Mitochondria

Answer 21

Site of cellular respiration: the conversion of energy from sugars to ATP.
Contain several small folds within that are called cristae which increase the surface areas for cellular respiration.
Within these folds is the mitochondrial matrix which contains DNA and ribosomes.

Question 22

Chloroplasts

Answer 22

(Only in plant cells)
Function to convert light energy into chemical energy via photosynthesis.

The inner membrane has thick fluid called stroma which holds DNA, ribosomes, and enzymes.

In the stroma is thylakoids which contains pigment called chlorophyll.
(Note: a stack of thylakoids = granum

Question 23

What is the endosymbiont theory?

Answer 23

States that mitochondria and chloroplasts were originally small prokaryotes or undigested bacteria in eukaryotic cells.

This is because they have their own DNA, their ribosomes are similar to prokaryotic ones, and they have double membranes

Question 24

Cytoskeleton

Answer 24

A network of small protein fibres found throughout the cytoplasm.
Provides structural support for cells.

3 kinds of fibres making up the cytoskeleton:
1) microfilaments
2) intermediate filaments
3) microtubules

Question 25

Microfilaments

Answer 25

Made from twisted rods of actin protein.

Function: form a 3D network in the plasma membrane that will support the cells shape.

Question 26

Intermediate filaments

Answer 26

Bigger than microfilaments;

Made from several fibrous proteins that coil together to make a thick cable.

Function: reinforce cell shape and anchor certain organelles such as the nucleus.

Question 27

Microtubules

Answer 27

Bigger than intermediate filaments;

Made from tubulin protein which forms a hollow tube.

Function: help maintain cell shape and combine with motor proteins to act as a track that helps organelles move in the cell.

Question 28

Centrioles

Answer 28

Small clusters of microtubules arranged in a bundle.

Function: help in cell division

Question 29

Cilia and flagella

Answer 29

Both serve to move the cell through any environment OR move fluid over the surface of the cell.

Cilia : short and numerous
Flagella : long and few in number

Question 30

Extracellular matrix

Answer 30

In animal cells, there is an excretion of an extracellular matrix of proteins and collagen that helps hold tissues together and support the plasma membrane .

Question 31

Cell junctions

Answer 31

Allow cells to interact with each other

3 types:
1) Tight junctions
2) Anchoring junctions
3) Gap junctions

Question 32

Tight junctions

Answer 32

Bind cells together using proteins and form a leak-proof barrier between the cells.

Question 33

Anchoring junctions

Answer 33

Attach cells together with cytoskeleton fibres, still allowing some material to pass between the cells.

Question 34

Gap junctions

Answer 34

Protein-lined pores that connect cells allowing certain ions (such as water) to flow through

Question 35

Cell wall

Answer 35

(Only in plants)
Not only do they hold the contents of the plant cell, but it has small holes which allow communication between plant cells.

Question 36

The Biogenic Law

Answer 36

“All living cells arise from pre-existing cells”
- Rudolf Virchow

Question 37

The endomembrane system

Answer 37

Consists of organelles that work together in at the synthesis, distribution, storage and export of molecules.

Organelles: nuclear envelope, both endoplasmic reticulums, Golgi, lysosomes, vacuoles, plasma membrane

Question 38

Which organelles have double membranes?

Answer 38

Nucleus, Mitochondria, and Chloroplasts