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Biology IB > 1.1 Cell introduction > Flashcards

1.1 Cell introduction Flashcards

1
Q

Cell Theory states that…

A
  1. All living things are composed of cells (or cell products)
  2. The cell is the smallest unit of life(nothing smaller an survive)
  3. Cells only arise from pre-existing cells; exception last unknown common ancestor
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2
Q

Caveats to the Cell Theory

A

Striated muscles
Giant Algae
Aseptate Hyphae

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3
Q

striated muscle

A

composed of the fusion of the cells to form fibres that consequently are multinucleated despite being surrounded by a single, continuous plasma membrane.
Challenges the idea that cells always function as autonomous units.

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4
Q

Giant Algae

A

unicellular organisms that are very large in size (eg. Acetabularia may exceed 7 cm length).

Challenges the idea that larger organisms are always made of many microscopic cells.

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5
Q

Aseptate hyphae

A

Fungi may have filamentous structures called hyphae, which are separated into cells by internal walls called septa, some fungi are not partitioned by septa and have a continuous cytoplasm.

Challenges the idea that living structures are composed of discrete cells.

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6
Q

Functions of Life

A

All living things carry out 7 basic functions integral to survival.

Metabolism
Reproduction
Sensitivity
Homeostasis
Excretion
Nutrition 
Growth
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7
Q

Metabolism

A

Undertaking essential Chemical reactions

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8
Q

Reproduction

A

Produce offspring, either sexually or asexually

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9
Q

Sensitivy

A

Responsive to an internal or external stimuli

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10
Q

Homeostasis

A

mantain a stable internal environment

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11
Q

Excretion

A

Exhibit the Removal of waste products

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12
Q

Nutrition

A

Exchange materials and gases with the environment

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13
Q

Growth

A

can move and change shape or size

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14
Q

Unicellular Organisms

A

are the smallest organisms capable of independent life and are able to carry ALL the life functions

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15
Q

Rate of metabolism

A

of a cell is a function of its mass / volume (larger cells need more energy to sustain essential functions)

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16
Q

Rate of material exchange

A

is a function of its surface area (large membrane surface = more material movement)

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17
Q

As a cell grows…

A

volume increases faster than surface area, leading to a decreased SA:Vol ratio

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18
Q

If metabolic rate exceeds the rate of exchange of vital materials and wastes (low SA:Vol ratio)

A

The cell will eventually die

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19
Q

Why cells tend to divide?

A

to remain small in order to maintain a high SA:Vol ratio suitable for survival

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20
Q

Increasing SA:Vol Ratio

A

→ Cells and tissues that are specialised for exchanges will increase their surface area to optimise material transfer.

→ Intestinal tissue of the digestive tract may form a ruffled structure (villi) to increase the surface area of the inner lining

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21
Q

Calculation of magnification

A

Magnification = Image size (with ruler) ÷ Actual size (according to scale bar)

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22
Q

Calculation of Actual size

A

Actual Size = Image size (with ruler) ÷ Magnification

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23
Q

Light microscopes

A

use lenses to bend light

24
Q

Light microscopes characteristics

A

→ Can view living specimens in natural colour

→ Have lower magnification and resolution

25
Electron Microscopes
use electromagnets to focus electrons
26
Electron Microscopes Characteristics
→ Can only view dead specimens in monochrome → Have higher magnification and resolution →Can show cross-sections (TEM) or surface renderings (SEM
27
Emergent properties
→ Multicellular organisms have properties that emerge from the interaction of their cellular components
28
Emergent properties arise when...
when the interaction of individual component produce new functions
29
In multicellurar Organisms
``` Cell > Tissue> Organ> System> Organism> ```
30
Unicellular Organisms evolved
to Multicellular Organisms
31
from smaller to larger
membrane thickness > virus > bacteria
32
Example of emergent properties
An example of an emergent property is the increased levels of antibiotic resistance that can be seen in bacterial biofilms
33
Differentiaton
is the process during development whereby newly formed cells become more specialised and distinct from one another as they mature
34
All cells of an organism share an identical genome;
so each cell contains the entire set of genetic instructions for that organism.
35
Genome
A genome is the complete set of genetic information in an organism. It provides all of the information the organism requires to function.
36
Gene packaging
Within the nucleus of a eukaryotic cell, DNA is packaged with proteins to form chromatin
37
Active Genes
are usually packaged in an expanded form called euchromatin that is accessible to transcriptional machinery
38
Inactive Genes
are typically packaged in a more condensed form called heterochromatin (saves space, not transcribed)
39
Chromatin
Chromatin is the material that makes up a chromosome that consists of DNA and protein. The major proteins in chromatin are proteins called histones. They act as packaging elements for the DNA.
40
Stem Cells
Stem cells are special human cells that are able to develop into many different cell types. This can range from muscle cells to brain cells. In some cases, they can also fix damaged tissues
41
Stem cells are unspecialised cells that have two key qualities:
1. Self Renewal: They can continuously divide and replicate | 2. Potency: They have the capacity to differentiate into specialised cell types
42
Types of stem cells
Totipotent: Can form any cell type, as well as extra-embryonic tissue Pluripotent: Can form any cell type Multipotent: Can differentiate into a number of closely related cell types Unipotent: Can not differentiate, but are capable of self renewal
43
Uses of stem cells
Stem cells are necessary for embryonic cell development as they are an undifferentiated cell source from which all other cell types may be derived Cell types that are not capable of self-renewal (e.g. amitotic nerve tissues) are considered to be non-stem cells.
44
Stem cells can be used to REPLACE DAMAGED OR DISEASED CELLS | This process requires:
- The use of biochemical solutions to trigger the differentiation of stem cells into the desired cell type - Surgical implantation of cells into the patient’s own tissue - Suppression of host immune system to prevent rejection of cells (if stem cells are from foreign source) - Careful monitoring of new cells to ensure they do not become cancerous
45
Stargardt’s disease
- An inherited form of juvenile macular degeneration that causes progressive vision loss to the point of blindness - Caused by a gene mutation that impairs energy transport in retinal photoreceptor cells, causing them to degenerate - Treated by replacing dead cells in the retina with functioning ones derived from stem cells
46
Leukemia
Bone marrow transplants (Trasplantes de médula ósea) for cancer patients who are immunocompromised as a result of chemotherapy
47
Paraplegia
Repair damage caused by spinal injuries to enable paralysed victims to regain movement
48
Diabetes
Replace non-functioning islet cells (se encuentran en el páncreas) with those capable of producing insulin in type I diabetics
49
Burn victims
Graft new skin cells to replace damaged tissue
50
Embryonic stem cells
embryos can be created by fertilizing eggs cells with sperm and allowing the resulting zygote to develop for a few days until it has between 4 and 16 cells. May be specially created by therapeutic cloning.
51
Cord Blood Stem Cells
blood can be extracted from the umbilical cord of a new-born baby and stem cells obtained from it. The cells can be frozen and stored for possible use later in the baby’s life.
52
Adult Stem Cells
stem cells can be obtained from some adult tissues such as bone marrow. Not pluripotent.
53
Somatic Cell Therapy
Involves the creation of embryonic clones by fusing a diploid nucleus with an enucleated egg cell (therapeutic cloning)
54
What do need cells to survive?
- production of chemical energy | - exchange of materials with the environment
55
Nuclear Reprogramming
Induce a change in the gene expression profile to transform it into a different cell type (transdifferentiation), increases the risk consequences
56
Enzymes
acts as a catalyst to bring about a specific biochemical reaction.

Biology IB (8 decks)

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