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Biology HL > 1.1 Introduction to cells > Flashcards

1.1 Introduction to cells Flashcards

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1
Q

what does the cell theory state?

A

it states that cells are fundamental building blocks of all living organisms

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2
Q

what can we see if, for example, we dissect kidneys?

A

we can see that large organs are made up of a number of different tissues

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3
Q

when did biologists start using microscopes?

A

17th century

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4
Q

what are the smaller organisms made up of?

A

they consist of just 1 cell–> they are unicellular

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5
Q

what do we know about the internal structure of a living organism?

A

the internal structure of a living organism is intricate and built from small parts

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6
Q

what are the larger organisms made up of?

A

they are composed of many cells –> they are multicellular

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7
Q

what are 4 common features of cells

A

1) are surrounded by a membrane that separates the cell content from the outside
2) they contain genetic material which stores instruction for cell activities
3) these activities are called chemical reactions and are catalyzed by enzymes produced inside the cell
4) they have their own energy release system that powers cell activities

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8
Q

at an early stage in scientific investigation, what is the researcher looking for?

A

trends and discrepancies in a wide range of experiments

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9
Q

definition of a trend in an experiment

A

things that appear to be found generally

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10
Q

what do trends and discrepancies lead to?

A

the development of a theory

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11
Q

definition of a scientific theory

A

way of interpreting the natural world and which allows predictions to be made

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12
Q

define discrepancies

A

some exceptions which can be serious or common enough to make predictions that are too unreliable to be useful

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13
Q

who was the first person to use the word “cell” for structures in living organisms?

A

Robert Hooke

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14
Q

when did Robert Hooke examine parts of plants

A

1665

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15
Q

why was the cell theory not discarded?

A

Many tissues consist of cells ì, but some discrepancies have been discovered. For example, organisms that d not consist of typical cells. Despite this, the theory was not discarded because there are MANY tissues consisting of cells and just a few discrepancies.

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16
Q

microscopes show structures larger or smaller than they actually are?

A

larger

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17
Q

how many levels of magnification are there?

A

3:

1) x40–> low
2) x100–> medium
3) x400–> high

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18
Q

definition of a micrograph

A

a photo taken by a microscope

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19
Q

when drawing a specimen, is it necessary for the magnification to be the same of the microscope?

A

no

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20
Q

how do you find the magnification of a micrograph or drawing?

A

actual size of the specimen

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21
Q

What is the first atypical example to look at when testing the cell theory and why?

A

Striated muscle because it has building blocks which are muscle fibres that are similar in some ways to cells

  • surrounded by a membrane
  • formed by a division of pre-existing cells
  • have their own genetic material and energy release system
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22
Q

What is the second atypical example to look at when testing the cell theory and why?

A

Fungi because: ( structures are called hyphae)

  • have a cell membrane and cell wall
  • they are divided into small cell-like sections by cross walls called septa
  • each hypha is an uninterrupted tube-like structure with many nuclei spread along it
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23
Q

What is the third atypical example to look at when testing the cell theory and why?

A

Algae because:

  • store their genes inside the nucleus
  • they have a simpler structure and organization compared to plants
  • many consists of 1 microscopic cell–> most of them are in the ocean and are the basis of most marine food chains
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24
Q

definition of giant algae

A

algae that grow to a much larger size but are still single-celled

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25
Q

definition of “functions of life”

A

things that all organisms must do to stay alive

26
Q

why is the structure of unicellular organisms more complex?

A

because just one cell has to carry out all the functions

27
Q

what are the 7 functions of life that unicellular organisms carry out?

A

1-nutrition
2-metabolism (chemical reactions in the cell)
3-growth
4-response
5-excretion
6-reproduction
7-Homeostasis (keeping conditions inside the organism within tolerable limits)

28
Q

what is the metabolic rate of the cell proportional to?

A

the volume of the cell

29
Q

what must happen for the metabolism to continue?

A

substances used in the reactions must be absorbed by the cell and waste products must be removed

30
Q

the rate at which substances move in and out of cells through plasma membrane depends on what?

A

the surface area

31
Q

what happens if the surface area is too small?

A

1- the substances will not enter the cell as quickly as they are required
2- waste products will accumulate because they are produced more rapidly than they are excreted
3- cells overheat because metabolism produces heat faster than it is lost over the cell’s surface

32
Q

some unicellular organisms live in?

A

colonies

33
Q

what does a colony consist of?

A

a ball made of a protein gell with 500 or more identical cells attached to its surface

34
Q

are unicellular organisms fused?

A

no, they are just cooperating

35
Q

definition of a multicellular organism

A

it consists of a single mass of cells fused together

36
Q

what are the characteristics of the Caenorhabditis elegans (worm) and why is it important?

A

It is the most intensively researched animal

  • the adult body is 1 mm long and has 959 cells( small n°)
  • has no common name
  • lives unseen in decomposing matter(it feeds on its bacteria)
  • it has a mouth, pharynx, intestine, and anus
  • it is a hermaphrodite
  • 173 of the cells are neurons or nerve cells that are located at the front end of the worm( animal’s brain)
  • brain does not control how individual cells develop
37
Q

what are cooperative group of cells?

A

any cell that acts as a leader in a multicellular organism

38
Q

what are emergent properties?

A

the characteristics of the whole organism that arise from the interaction of the component parts of a complex structure

39
Q

what is division of labour

A

when different cells perform different functions in multicellular organisms

40
Q

definition of tissue

A

it is a group of cells specialized in the same way to perform the same function

41
Q

why can cells in a tissue carry out their role more efficiently than if they had many different roles?

A

because they can develop the ideal structure with the enzymes needed to carry out all of the chemical reactions associated with the function

42
Q

definition of differentiation

A

it is the development of cells in different ways to carry out specific functions

43
Q

what do we mean when we say that a gene is expressed?

A

when the information in a gene is being used to make a protein or another gene product

44
Q

why does cell differentiation occur?

A

because a different sequence of genes is expressed in different cell types

45
Q

what can cells do in the early stages in embryonic development?

A

they are capable of dividing many times to produce large amounts of tissue and they are very versatile and can differentiate along different pathways

46
Q

what are the 2 properties that make early stages in embryonic development the most active areas of research in biology and medicine?

A

1- they can divide again and again to produce copious quantities of new cells which is useful for the growth of the tissue and replacement of cells that have been lost or damaged
2- they are not fully differentiated

47
Q

what are the 3 main therapeutic uses of embryonic stem cells

A

1- produce regenerated tissue
2-heal diseases
3-grow whole replacement organs

48
Q

what is 1 main non-therapeutic use of embryonic stem cells

A

producing striated muscle fibres, or meat, for human consumption

49
Q

How does differentiation take place?

A

Early-stage embryonic stem cells are very versatile. Gradually, they commit to a pattern of differentiation. They are points at which a cell decides whether to develop along a certain pathway

50
Q

What are cells able to do once they have committed to differentiation

A

they are able to divide in the same way and they are no longer stem cells

51
Q

There is a small number of stem cells in the adult body, where can we find them, and what is their role?

A
  • bone marrow, skin, and liver= powers of regeneration and repair
  • brain, kidney and heart= allow limited repair
52
Q

Give the full explanation of Stargardt’s disease

A

It is a genetic disease noticed in children between 6-12. There is a recessive mutation of the gene ABCA4 which causes a membrane protein, used for active transport in retina cells, to malfunction. Photoreceptive cells in the retina degenerate, which are cells that detect light, and the vision becomes worse

53
Q

What was the first method used to cure Stargardt’s disease?

A

They were initially tested on mice. They were injected into the eye and caused no harm but the vision improved. Inside, the cells moved to the retina where they attached and remained.

54
Q

Give the full explanation of Leukemia

A

It is a type of cancer in which mutations occur in genes that control white blood cell division. Therefore there is a large number of white blood cells produced in the bone marrow.

55
Q

what must be done to cure leukemia

A

Cancer cells must be destroyed by treating a patient with chemicals, called chemotherapy.

56
Q

What is the procedure to cure leukemia using stem cells?

A

1-needle is inserted into the bone and the fluid is removed
2-stem cells are extracted and freeze for the potential to produce blood cells
3-chemotherapy drugs are given to kill cancer cells. Therefore bone marrow loses its ability to produce blood cells
4- stem cells are returned to the body. They re-establish themselves in the bone marrow, multiply and start to produce red and white blood cells

57
Q

what are the 3 sources of stem cells

A

1- embryos:
They are created by fertilizing egg and sperm cells. Allowing the zygote to develop until it has 4-16 cells is considered embryonic stem cells.
2- blood:
It is extracted from the umbilical cord of a newborn baby and stem cells are obtained. It is then frozen and stored.
3- stem cells obtained from an adult’s bone marrow

58
Q

which of the 3 sources of stem cells( embryo, blood, adult’s bone marrow) is easily obtainable?

A

The easiest is embryos, then blood then the hardest is adult

59
Q

which of the 3 sources of stem cells( embryo, blood, adult’s bone marrow) can differentiate more?

A

embryos, then blood then the hardest is adult

60
Q

which of the 3 sources of stem cells( embryo, blood, adult’s bone marrow)has less risk of becoming a tumour?

A

The least risky is adult, then blood then the riskiest embryo

61
Q

which of the 3 sources of stem cells( embryo, blood, adult’s bone marrow) is the safest to remove?

A

The safest are both adult and blood and embryos are killed

Biology HL (2 decks)

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