Chapter 1.1 - Intruduction to Cells

Question 1

What does the Cell Theory state?

Answer 1

• all living organisms are composed of one (unicellular) or many (multicellular) cells
• cells are the smallest units of life
• cells come from other cells which already exist

Question 2

What are the 4 features that every cell shares?

Answer 2

• Every living cell is surrounded by a membrane
• Cells contain genetic material
• Cell‘s activities are maintained by chemical reactions (catalysed by enzymes)
• Cells have their own energy release system

Question 3

How is a theory developed?

Answer 3

• scientist find general trend to interpret the natural world and to be able to make predictions
• if exceptions=discrepancies are common/serious enough the theory will be discarded, because the predictions would be unreliable

Question 4

What would be the holistic answer to the question: „What is the unit of life: the human or its cells?“?

Answer 4

the human

Question 5

What would be the reductionist answer to the question:”What is the unit of life: the human or its cells?”

Answer 5

Its cells

Question 6

How can you calculate the magnification of an image?

Answer 6

Magnification=size of image/actual size of specimen

Question 7

Name 3 examples for the exceptions of cell theory

Answer 7

• striated muscle
• giant algae
• aseptate fungal hyphae

Question 8

Why is striated muscle an exception to cell theory?

Answer 8

• much larger than most animal cells

- instead of one nucleus, they habe many- sometimes several hundred

Question 9

Why is Aseptate Hyphae an exception to cell theory?

Answer 9

• hyphae are usually divided into sections by septa

- in aseptate fungi there are no septa=uninterrupted tube-like structure with many nuclei

Question 10

Why are algae an exception to cell theory?

Answer 10

-They get up to 100 mm long, but consist of only one cell

Question 11

What are the seven functions of life?

Answer 11

-Metabolsim
-Reproduction
-Growth
-Response
-Excretion
-Homeostasis
-Nutrition
(Mr. Grehn)

Question 12

How can you define Metabolism?

Answer 12

Chemical reactions inside the cell

Question 13

How can you define Reproduction?

Answer 13

Producing offspring (new organism of the same type)either sexually or asexually

Question 14

How can you define Growth?

Answer 14

ability to change or increase in size over time, may be limited in amount

Question 15

How can you define Response?

Answer 15

the ability to react to stimulus in the environment

Question 16

How can you define Excretion?

Answer 16

getting rid of the waste products of metabolsim

Question 17

How can you define Homeostasis?

Answer 17

keeping conditions inside the organism within tolerable limits

Question 18

How can you define Nutrition?

Answer 18

ability to convert materials from the external environment into usable forms

Question 19

What is the limitation on cell size?

Answer 19

surface area to volume ratio (is proportional to the metabolic rate of the cell)

Question 20

Should the surface area to volume ratio be rather small or rather big?

Answer 20

It should be rather big:

• large surface area
• small volume

Question 21

Which two processes in a cell depend on the surface area to volume ratio?

Answer 21

• metabolism

- heat production

Question 22

Why does the metabolism depend on the surface area to volume ratio?

Answer 22

if the ratio is too small then

• substances needed for chemical reactions will not enter the cell as quickly as they are required
• waste products will accumulate, because they are produced more rapidly than they can be excreted

Question 23

What would be an example for a cell with a healthy surface area to volume ratio?

Answer 23

11:1

Question 24

How can you define Organism?

Answer 24

anything showing all the features of life

Question 25

Why does the heat production and loss depend on the surface area to volume ratio?

Answer 25

if the surface area to volume ratio is too small then

• the metabolism produces heat faster than it is lost over the cell’s surface
• cells may overheat

Question 26

What is an emergent property?

Answer 26

An emergent property of a system is not a property of any one component of the system, but it is a property of the system as a whole.

Question 27

Can emergent properties be predicted with an reductionist approach?

Answer 27

No, although the reductionist approach had a large success when it comes to molecular biology, the holist approach is much better to find out emergent properties

Question 28

What would be a phrase that sums up emergent properties?

Answer 28

The whole is greater than the sum of its parts.

Question 29

What is a tissue?

Answer 29

• A group of cells with similar structure and function within a multicellular organism
• They get this structure and function by differentiation

Question 30

What is cell differentiation?

Answer 30

A process cells go through to become differentiated/specialized

Question 31

What benefits do specialized cells have?

Answer 31

A specialized cell carry out certain functions more efficiently.
Cells that are specialized in the same way form a tissue

Question 32

How does cell differentiation work?

Answer 32

-all cells have the same set of genes
-not all genes are needed in every cell
-if a gene is needed it is “expressed” or “switched on”
Cell differentiation happens because a different sequence of genes is expressed in different cell types

Question 33

When does a new animal life start?

Answer 33

A new animal life starts when a sperm fertilizes an egg cell to produce a zygote

Question 34

What are stem cells?

Answer 34

Stem cells are not yet differentiated cells, they may become differentiated when cells are needed in a certain area

Question 35

Where can you find stem cells?

Answer 35

You can find them nearly everywhere in the human body, but they are most important for the development of an embryo and in the bone marrow

Question 36

What are the two key properties of stem cells that make them so interesting for research?

Answer 36

• they can divide and produce copious quantities of new cells
• they are not yet differentiated, so they can differentiate to produce every cell type

Question 37

In which cases could stem cells be very helpful in future?

Answer 37

• produce regenerated tissue
• healing diseases like diabetes type 1
• grow whole replacement organs
• producing striated muscle =meat