1.1 Introduction to cells

Question 1

What are the 3 principles of the cell theory?

Answer 1

·All living organisms are composed of cells (or cell products)
·The cell is the smallest unit of life
·Cells only arise from pre-existing cells

Question 2

3 Caveats to the cell theory:
STRIATED MUSCLE

Answer 2

They have multiple nuclei despite being surrounded by a single continuous plasma membrane-challenges the idea that cells function as autonomous units

Question 3

3 Caveats to the cell theory:
ASEPTATE FUNGAL HYPHAE

Answer 3

Fungi may have hyphae separated into cells by septa (internal walls). Some are not partitioned by septa, having a continuous cytoplasm along the hyphae-challenges the idea of living structures boing composed by discret cells

Question 4

3 Caveats to the cell theory:
GIANT ALGAE

Answer 4

Some unicellular algae may grpw to very large sizes-challenges the idea that largaer organisms are always made of many microscopic cells

Question 5

Functions of life

Answer 5

MRSHENG
Metabolism
Reproduction
Sensitivity
Homestasis
Excretion
Nutrition
Growth

Question 6

Metabolism

Answer 6

Living things undertake undertake essential chemical reactions

Question 7

Reproduction

Answer 7

Living things produce offspring, either sexually or asexually

Question 8

Sensitivity

Answer 8

Living things are responsive to internal and external stimuli

Question 9

Homeostasis

Answer 9

Living things maintain a stable internal enviroment

Question 10

Excretion

Answer 10

Living things exhibit the removal of waste products

Question 11

Nutrition

Answer 11

Living things exchange materials and gases wiith the enviroment

Question 12

Growth

Answer 12

Living things can move and change shape or size

Question 13

What is the RATE OF METABOLISM dependent of?

Answer 13

The mass/volume. Larger cells need more energy to sustain essential functions

Question 14

What is the RATE OF MATERIAL EXCHANGE dependent of?

Answer 14

The surface area. Large membrane surface is equal to more material movement

Question 15

What happens with the SA:Vol ratio when the cell grows?

Answer 15

Volume (units3) increases faster than surface area (units2), leading to a decrease in SA:Vol ratio

Question 16

WHat happens when the metabolic rate exceeds the rate of exchange of vital material (low SA:Vol)? What do growin cells do to prevent it?

Answer 16

The cell will die. Growing cells tend to divide and remain small inorder to maintain a high SA:Vol ratio

Question 17

What is the magnification formula?

Answer 17

Magnification=image size(ruler)/actual size (scale bar)

Question 18

What are the 4 emergent properties from the interaction of multicelular organisms?

Answer 18

·Cells may goup together to form tissues
·Organs are then formed from the grouping of multiple tissues
·Organs that interact may form organ systems capable of carrying out specific body functions
·Organ systems collectively carry out the life functions of the complete organism

Question 19

What is differentiation and how does it work?

Answer 19

The process where newly formed cells become more specialised from one another as they mature. This happens with the activation of different genes within a cell by a chemical signal

Question 20

How are active genes packed?

Answer 20

In expanded form called EUCROMATIN which is accesible to transcription machinery

Question 21

How are inactive genes packed?

Answer 21

In condensed form called HETEROCROMATIN which saves space and is not transcribed

Question 22

What are stem cells?

Answer 22

Unspecialised cells with the 2 key qualities of:
·Self renewal: can continuously divide and replicate
·Potency: capacity to differentiate into specialised cell types

Question 23

TOTIPOTENT stem cells…

Answer 23

…can form any cell type, as well as extra-embryonic tissue (e.g zygote)

Question 24

PLURIPOTENT stem cells…

Answer 24

…can form any cell type (e.g embryonic stem cells)

Question 25

MULTIPOTENT stem cells…

Answer 25

…can differentiate into a number of closely related cell typed (e.g hematopoetic stem cells)

Question 26

UNIPOTENTS stem cells…

Answer 26

…can’t differentiate but are capable of self renewal (e.g muscle stem cells)

Question 27

4 steps of stem cell therapy

Answer 27

·Biochemical solution triggers the differentiation of the cel to the desired cell type
·Surgical implantation into patients own tissue
·Supresion of host immune system to prevent rejection
·Careful monitoring to ensure new cells do not become cancerous

Question 28

EXAMPLE STEM CELL THERAPY: Stagart’s Disease

Answer 28

·Juvenile macular degeneration that causes vision loss and even blindness. Caused by gene mutation imparing energy transport in retinal photoreceptor cell whic causes them to degenrate. Treated by replacing dead cells with functioning ones derived from stem cells.

Question 29

EXAMPLE STEM CELL THERAPY:
Parkinson’s Disease

Answer 29

Degenerative disorder of central nervous system caused by the death of dopamine secreting cells. Dopamine is responsible for transmiting signals involved in the production of smooth movement. Treated by replacing dead nerve cells with living, dopamine producing ones.

Question 30

Where can stem cells be derived from?

Answer 30

·Embryos (requires the destruction of a potential living organism but has greater yield)
·Umbilical chord blood or placenta of a newborn baby
·Some adult tissues like the bone marrow

Question 31

ARTIFICIAL STEM CELL TECHNIQUES:
Somatic Cell Nuclear Transfer (SCNT)

Answer 31

Creation of embryonic clones by fusing a diploid nucleus with an enucleated egg cell. More embryos are created than needed in this process raising ethical concerns

Question 32

ARTIFICIAL STEM CELL TECHNIQUES:
Nuclear Reprograming

Answer 32

Induces a change in the gene expresion profile of a cell in order to transform it into a different cell type (transdifferentiation). Involves the use of oncogenic retroviruses and transgenes, increasing the risks of health consequences such as cancer