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Biology Topic 1 > Introduction to Cells > Flashcards

Introduction to Cells Flashcards

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1
Q

What are the three principles of cell theory?

A
  1. All living organisms are made of one or more cells.
  2. All cells are made of PRE-EXISTING cells.
  3. The cell is the most basic unit of organization in organisms.
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2
Q

What is the exception to a trend called in biology?

A

A discrepancy

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3
Q

How should you draw the lines on your cell drawings?

A

Single sharp lines with a sharp pencil.

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4
Q

How should lines be connected in cell drawings?

A

They should be joined up carefully to create continuous structures.

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5
Q

When do we use freehand and when do we use a ruler when drawing cells?

A

Freehand for the drawings themselves but a ruler for label lines.

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6
Q

What are the usual levels of magnification on a school microscope?

A

40 times, 100 times, 400 times

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7
Q

What is a micrograph?

A

A photograph or digital image taken through a microscope.

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8
Q

The length of an image is 30mm. It represents a structure that has an actual length of 3µm. Determine the magnification of the image.

A

10,000×

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9
Q

How many µm is 50mm?

A

50000µm

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10
Q

How do you find the length of a cell?

A

Measure the longest side. Start from the longest part!?

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11
Q

How do you find the magnification of an image?

A

The magnification of an image is (measured size of the drawing) / (size of specimen)

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12
Q

Why is the striated muscle cell an exception to cell theory, and what does it suggest?

A

Because it is much larger than most cells (about 30mm) and they have many nuclei. Challenges the idea that cells always function as autonomous units

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13
Q

Why is aseptate hypha an exception to cell theory, and what does it suggest?

A

Most fungi have cell partitions called septa. However aseptate hyphae do not, and hence have a continuous cytoplasm with many nuclei along it. Challenges the idea that living structures are composed of discrete cells

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14
Q

Why is the Acetabularia an exception to normal cells (cell theory)?

A

It is a 0.5-10cm plant that only has one nucleus, meaning that the whole plant is a single cell.Challenges the idea that larger organisms are always made of many microscopic cells

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15
Q

What is a unicellular organism?

A

A unicellular organism is an organism consisting only of one cell.

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16
Q

What does MR H GREN stand for?

A

Metabolism, Response, Homeostasis, Growth, Reproduction, Excretion, Nutrition

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17
Q

What does metabolism mean? Give an example.

A

Metabolism refers to how living things have many different chemical reactions happening inside them (Eg. Humans convert food into energy, Enzymes in paramecium create a chemical reaction to digest food)

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18
Q

What does response mean? Give an example in humans and cells.

A

Response refers to how living things react to stimuli/the environment (Eg. Humans’ pupils constrict or dilate in the light, Paramecium avoids too hot or cold water)

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19
Q

What does homeostasis mean? Give an example in humans and cells.

A

Homeostasis refers to how living things can maintain conditions within themselves (Eg. Body temperature in humans, Paramecium expels water to manage the water content)

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20
Q

What does growth mean? Give an example in humans and cells.

A

Growth refers to how living things can change size and shape. (Eg. Humans grow taller, Paramecium gets larger after consuming biomass)

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21
Q

What does reproduction mean? Give an example in humans and cells.

A

Reproduction refers to how living things can make more of themselves either sexually or asexually. (Eg. Humans reproduce sexually to create offspring, Paramecium divide asexually through binary fission )

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22
Q

What does excretion mean? Give an example in humans and cells.

A

Excretion refers to how living things can get rid of waste products. (Eg. Sweat and defecation in humans, Paramecium expels metabolic waste)

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23
Q

what does nutrition mean? Give an example in humans and cells.

A

Nutrition refers to how living things can obtain food to create energy. (Eg. Humans convert food into energy, Paramecium consumes food and stores them in vacuoles)

24
Q

What happens to cells as they become bigger? (Long answer)

A

As cells become bigger, the surface area to volume ration decreases. In order for a cell to be able to perform metabolism, it must exchange materials and wastes by diffusion through the cell membrane. If the cell has a low SA:Volume ratio, the cell will not be able to perform diffusion efficiently. If the metabolic rate (volume) exceeds the rate of exchange of vital materials (surface area) the cells will die.

25
Q

Why do big organisms tend to be multicellular?

A

This is because if a big organism was one cell, it would have a low SA: volume ratio which would not allow the cells to function well. Their many cells allow metabolism and efficiency.

26
Q

What is villi and microvilli?

A

Villi is a ruffled structure on cells that allow for more SA, and microvilli are small membrane extensions that also allow for more SA.

27
Q

What are emergent properties?

A

Emergent properties are when multiple components of something work together to perform a new function that cannot be done by any of the individual components alone. An example of this would be how the heart, which is comprised of heart cells, pumps blood around the body. This cannot be done by a single heart cell.

28
Q

What is cell differentation?

A

Cell differentation is the process during the development of newly formed cells where they become specialized to perform different functions.

29
Q

How do cells become differentiated?

A

Cells become differentiated through gene expression. This is where, during the process of cell development, some genes in the cell are switched off while others are switched on. This gives instructions to the cell to perform their specialized function.

30
Q

What are stem cells?

A

Stem cells are undifferentiated cells, that are usually found in the embryo of multicellular organisms, that are characterized my the properties of self renewal and potency.

31
Q

What does self renewal mean?

A

The quality of being able to divide again and again to produce new cells.

32
Q

What does potency mean?

A

The quality of a cell being unspecialized.

33
Q

What is the use of stem cells to cure diseases called?

A

Therapeutic use

34
Q

What cells are affected in Stargardt’s disease?

A

Photoreceptive cells of the retina

35
Q

When are stem cells at their most versatile?

A

At their most early stage in the embryo.

36
Q

How can stem cells help cure Stargardt’s?

A

Embryonic stem cells that have been artificially specialized into retina cells are injected into the eye, where they will attach to the retina and improve vision.

37
Q

How can stem cells help cure Leukemia?

A

Stem cells are extracted from the patient’s bone marrow and frozen while the patient undergoes chemotherapy. The patient will then lose their ability to produce blood cells. After chemotherapy is completed they are injected into the patient’s body and begin to multiply, producing new blood cells.

38
Q

How is differentiation triggered in the therapeutic use of stem cells?

A

The use of biochemical solutions trigger differentiation.

39
Q

What are two risks when foreign stem cells are inserted into a patient’s body?

A

There is a risk of the patient rejecting the foreign cells, and a risk of the cells becoming cancerous.

40
Q

What are multipotent stem cells?

A

Multipotent stem cells are stem cells that can differentiate into a number of closely related cell types.

41
Q

What are totipotent stem cells?

A

Totipotent stem cells are stem cells that can form any cell type, INCLUDING extra embryonic tissue and placental cells.

42
Q

What are pluripotent stem cells?

A

Pluripotent stem cells are cells that can from any cell type.

43
Q

What are unipotent stem cells?

A

Unipotent stem cells can not differentiate, but retain their quality of self renewal.

44
Q

Where can stem cells be derived from?

A

Embryos, umbilical cord blood, and certain adult tissues such as bone marrow and skin.

45
Q

Why can stem cell research be controversial?

A

Because stem cell research can often include the killing of an early stage embryo, and some people believe that early stage embryos hold the same value as an individual human life.

46
Q

What is a scale bar

A

A means of visually indicating the magnification of an image.

47
Q

What is tissue?

A

A group of cells with a common function and structure

48
Q

What is an electron microscope?

A

A type of microscope that was developed in the 1930’s. They allowed for much higher resolution than light microscopes, allowing for new knowledge and discoveries.

49
Q

Define resolution

A

Making the separate parts of an object distinguishable by eye.

50
Q

What kind of microscope can produce 3D images of cells?

A

Scanning microscopes

51
Q

What is the resolution of a light vs electron microscope?

A

light microscope is up to 0.2 micrometers, electron microscope is up to 0.2 nanometers.

52
Q

What are some disadvantages of the electron microscope?

A

They are expensive, the preparation is complex, and the cells must be killed.

53
Q

What do prokaryotes have in the place of a nucleus, and what is it made of?

A

A nucleoid, which consists of DNA strands, as well as proteins and enzymes.

54
Q

What is the size of the ribosomes in prokaryotes, and what is the S used to represent it?

A

Ribosomes in prokaryotes are 70S. The S stands for Svedberg, and refers to a measuring unit for sedimentation speed.

55
Q

What is the difference between mitosis and binary fission?

A

Both are asexual forms of production. Binary fission occurs in prokaryotes, while mitosis occurs in eukaryotes. Binary fission lacks a nucleus, while mitsosis does not.

56
Q

List three adaptations of cells that may function to maximise the surface area to volume ratio

A

Cells may reduce volume by adopting large central vacuoles (e.g. plant cells), cells may have long membranous extensions to increase S.A (e.g. microvilli), cells may have a elongated or flattened shape to increase area.

Biology Topic 1 (1 decks)

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