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Biology IB > 1.1 Cell introduction > Flashcards

1.1 Cell introduction Flashcards

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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
Q

Electron Microscopes

A

use electromagnets to focus electrons

26
Q

Electron Microscopes Characteristics

A

→ Can only view dead specimens in monochrome
→ Have higher magnification and resolution
→Can show cross-sections (TEM) or surface renderings (SEM

27
Q

Emergent properties

A

→ Multicellular organisms have properties that emerge from the interaction of their cellular components

28
Q

Emergent properties arise when…

A

when the interaction of individual component produce new functions

29
Q

In multicellurar Organisms

A 
Cell > 
Tissue>
Organ>
System>
Organism>
30
Q

Unicellular Organisms evolved

A

to Multicellular Organisms

31
Q

from smaller to larger

A

membrane thickness > virus > bacteria

32
Q

Example of emergent properties

A

An example of an emergent property is the increased levels of antibiotic resistance that can be seen in bacterial biofilms

33
Q

Differentiaton

A

is the process during development whereby newly formed cells become more specialised and distinct from one another as they mature

34
Q

All cells of an organism share an identical genome;

A

so each cell contains the entire set of genetic instructions for that organism.

35
Q

Genome

A

A genome is the complete set of genetic information in an organism. It provides all of the information the organism requires to function.

36
Q

Gene packaging

A

Within the nucleus of a eukaryotic cell, DNA is packaged with proteins to form chromatin

37
Q

Active Genes

A

are usually packaged in an expanded form called euchromatin that is accessible to transcriptional machinery

38
Q

Inactive Genes

A

are typically packaged in a more condensed form called heterochromatin (saves space, not transcribed)

39
Q

Chromatin

A

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
Q

Stem Cells

A

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
Q

Stem cells are unspecialised cells that have two key qualities:

A
  1. Self Renewal: They can continuously divide and replicate

2. Potency: They have the capacity to differentiate into specialised cell types

42
Q

Types of stem cells

A

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
Q

Uses of stem cells

A

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
Q

Stem cells can be used to REPLACE DAMAGED OR DISEASED CELLS

This process requires:

A
  • 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
Q

Stargardt’s disease

A
  • 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
Q

Leukemia

A

Bone marrow transplants (Trasplantes de médula ósea) for cancer patients who are immunocompromised as a result of chemotherapy

47
Q

Paraplegia

A

Repair damage caused by spinal injuries to enable paralysed victims to regain movement

48
Q

Diabetes

A

Replace non-functioning islet cells (se encuentran en el páncreas) with those capable of producing insulin in type I diabetics

49
Q

Burn victims

A

Graft new skin cells to replace damaged tissue

50
Q

Embryonic stem cells

A

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
Q

Cord Blood Stem Cells

A

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
Q

Adult Stem Cells

A

stem cells can be obtained from some adult tissues such as bone marrow. Not pluripotent.

53
Q

Somatic Cell Therapy

A

Involves the creation of embryonic clones by fusing a diploid nucleus with an enucleated egg cell (therapeutic cloning)

54
Q

What do need cells to survive?

A
  • production of chemical energy

- exchange of materials with the environment

55
Q

Nuclear Reprogramming

A

Induce a change in the gene expression profile to transform it into a different cell type (transdifferentiation),

increases the risk consequences

56
Q

Enzymes

A

acts as a catalyst to bring about a specific biochemical reaction.

Biology IB (8 decks)

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