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IB HL biology > (1) Cell Biology > Flashcards

(1) Cell Biology Flashcards

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1
Q

Outline cell theory

A

Proposed by Theodore Schwann
in 1839

1) All organisms are made of cells
2) Cells are the basic units of life
3) Cells come from pre-existing cells

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2
Q

History of cell theory

A

1626: Redi postulated that living things do not arise by spontaneous generation

1655: Hooke describes “cells” in cork

1674: Leeuwhenhoek discovers single celled organisms (prozos and bacteria)

1805: Oken states “all living organisms orginate from and consist of cells

1838: Schwann and Schleiden propose cell theory

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3
Q

Evidence for cell theory

A

1) All organisms are made of cells
→Microscope

2) Cells are the basic units of life
→ Microscopes were used to examine tissues, any part smaller than a cell (for example, any organelle) is not capable of independently carrying out all of the characteristics of life

3) Cells come from pre-existing cells
→ Miller-Urey Expirement

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4
Q

Functions of life

A

Movement: internally or externally
Reproduction: asexual or sexual
Growth: change shape and size
Respiration: use substances from the environment for energy
Excretion: removal of waste
Nutrition: exchanges materials from the environment
Sensitivity: respond and interact w environment

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5
Q

Calculating volume, surface area and ratio of a cube

A

Volume: BxHxW
SA: BxHx6

Ration: Surface area/ volume

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6
Q

Compare the relative size of:

viruses
molecules
bacterium
organelles
cell membrane thickness
plant cell
animal cells

A

molecules 1nm
cell membranes 10nm
virus 100nm
bacterium 1um
animal cell 1 um
plant cell 10um
organelles µm

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7
Q

Calculate linear magnification and scale

A

linear magnification: drawing/object
scale: object/drawing

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8
Q

State the importance of the SA/Volume ratio as a factor limiting cell size

A

-increase in volume = increase in SA
- rate of material exchange is proportional to SA
- rate of metabolism proportional to volume

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9
Q

multicellular organisms show emergent properties. elaborate.

A

Emergent properties are properties that become apparent and result from various interacting components within a system but are properties that do not belong to the individual components themselves

In multicellular organisms: Cells may be grouped together to form tissues. Organs are then formed from the functional grouping of multiple tissues.

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10
Q

Cells in multicellular organisms differentiate to….

A

Carry out different specialized functions by expressing and masking certain genes.

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11
Q

Stem cells can retain the capacity to _______ and have the ability to ________.

A

divide
differentiate along different pathways

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12
Q

Therapeutic use of stem cells

A

Stem cells can be used to replace damaged or diseased cells with healthy functioning ones

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13
Q

Osmosis

A

The passive movement of water/something across a semipermeable membrane

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14
Q

phagocytosis, pinocytosis, exocytosis

A
  • eat large cells and particles
  • drink waters and liquids
  • expel
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15
Q

isotonic value

A

when cells and environment solute concentrations are equal

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16
Q

Parts of a plant cell

A

cell wall: surrounds plasma membrane
plasma membrane: protects cell
pilli: help attach cell to surfaces
cytoplasm: medium for chemical interactions
nucleoid: controls activity of cell and reproduction
ribosome: makes protiens

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17
Q

Compare and contrast the structure of eukaryotic and prokaryotic cells

A

EUKARYOTIC
- naked DNA
- circular DNA
- no nucleus
- no membrane-bound organelles
- binary fission

SAME
- have DNA
- cytoplasm
- ribosomes

PROKARYOTIC
- DNA bound to protein
- linear DNA
- nucleus
- membrane-bound organelles
- mitosis and mesiosis

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18
Q

Prokaryotic cells divide by

A

binary fission

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19
Q

Compare and contrast the structure of plant and animal cells

A

PLANT
- cell wall
- chloroplasts
- definite shape

ANIMAL
- no cell wall
- lysosomes
- centiroles

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20
Q

Explain how the hydrophobic and hydrophilic properties of phospholipids help to maintain the structure of cell membranes.

A
  • Allows small substances like oxygen to pass through easily
  • Allows cells to change shape easily
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21
Q

Functions of membrane protiens

A
  • help cells communicate
  • help cells maintain shape
  • transport shared material
  • help cells carry out changes made by chemical reactions
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22
Q

Define diffusion

A

Diffusion: the passive movement of anything from hight to low concentration

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23
Q

Explain the role of protein pumps and ATP in active transport around membranes

A

During active transport, protein pumps use ATP to move molecules in an area of high concentration to an area of low concentration

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24
Q

Explain passive transport across membranes through simple diffusion and facilitated diffusion.

A

Simple: movement of particles moves in directions of the concentration gradient

Facilitated: moved any way

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25
Q

Explain passive transport across membranes through simple and facilitated diffusion.

A

simple: in the direction of the concentration gradient
facilitated: in any direction

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26
Q

Explain how vesicles are used to transport materials within a cell between the rough ER, golgi apparatus and plasma membrane

A

Proteins are synthesized by ribosomes and enter the rER. Vesicles bud off from the rER and carry proteins to the Golgi.
The Golgi modifies proteins, and then the vesicles bud off from the Golgi and carry modified proteins to the plasma membrane.

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27
Q

Describe how the fluidity of the membrane allows it to change shape, break and reform during endocytosis and exocytosis

A

Phospholipids in the cell membrane are in fluid state, allowing the membrane to change its shape and also vesicles to fuse with it.

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28
Q

Discuss the implications of all cells being formed from pre-existing cells

A

There must have been a first cell that arose from non-living material billions of years ago.

The origins of all cells can be traced back through billions of years of evolution to “LUCA” the last universal common ancestor of all life on Earth.

Cells in our bodies originate from the first cell: the zygote produced by the fertilization of a sperm and egg.

29
Q

Define spontaneous generation

A

The theory, now discredited, that living organisms can routinely emerge from nonliving matter independently of other living matter.

30
Q

Why did bacteria grow in the broth of the flask that was left open by Pasteur?

A

Because be being exposed to CO2, bacteria was able to manifest in the broth

31
Q

Explain why Pasteur’s experiment did not support spontaneous generation

A

Spontaneous generation did not occur in the flask not exposed to other elements (CO2)

32
Q

Explain the historical thinking for spontaneous generation

A

Early philosophers and scientists were basing their ideas on what they could observe at the time.

Technological tools had not yet advanced to the point of being able to observe cells arising from other cells.

There was no reason to show that spontaneous generation wasn’t accurate. It’s hard to speak out against an idea when a majority support it.

Spontaneous generation was consistent with the other widely held cultural and religious beliefs of the time.

33
Q

Define conformity bias and give a historical example

A

Conformity bias is the tendency to behave similarly to others in a group, against your own judgment. Conformity bias often stops creative or outside thinking. Historically conformity bias may have limited exploration into generation of living organism.

34
Q

Define endosymbiotic theory

A

Mitochondria and chloroplasts were once other cells that were engulfed by other cells and formed a symbiotic relationship.

35
Q

Evidence for the endosymbiotic theory

A

Mitochondria and chloroplasts have a double membrane and circular DNA

36
Q

State the function of mitosis

A

The process of cells dividing and creating genetically identical “daughter” cells

37
Q

list 4 processes that use mitosis

A

growth, repair, sexual reproduction, replacement

38
Q

draw the typical eukaryotic cells as they would appear during the interphase and the 4 stages of miosis.

A

(//) -> (xx) -> (x-x) -> (//-//) -> (//)(//)

39
Q

outline 4 events that occur during prophase

A

chromosome supercoil and become usable, centiroles move to opposite poles, mictrotubule spindles form between the centiroles, nucleous becomes invisible.

40
Q

outline the process of metaphase, inclusive of the role of microtubules and the kinetochore

A

stage 2 spindle microtubules fully develop and attach to the centromere region but specifically the kinetochore.

41
Q

outline process of anaphase

A

sister chromatids separate and are pulled towards opposite ends of cell. each is now its own chromosome

42
Q

outline the events that occur during telophase

A

the chromosomes arrive at the cell poles and the miotic spindle disassembles

43
Q

describe the structure of a replicated chromosome, including the centromere and sister chromatids

A

initally contains two identical DNA strands that are held together by the centromere -> X

44
Q

explain why chromosomes must condense during mitosis

A

so it can be moved to the two sides of the cell more easily.

45
Q

state the difference betweeen mitosis and cytokenesis

A

mitosis= division of the nucleus
cytokenesis= division of the cytoplasm both stages of the cell cycle

46
Q

contrast cytokenesis in plants and animals

A

PC= cytokenesis occurs through the formation of a cell plate
AC= cytokenesis occurs through the formation of a cleavage furrow

47
Q

list examples of metabolic reactions during interphase

A

protein synthesis

48
Q

G1

A

cell growth

49
Q

S

A

DNA synthesis

50
Q

G2

A

cell worth

51
Q

GO

A

miotic phase (mitosis and cytokenesis

52
Q

tumor

A

mass of tissue caused by abnormal growth

53
Q

benign

A

tumor that lacks the ability to invade other tissues and metastisize

54
Q

malignant

A

tumor made of cells that can invade other tissues and metastisize

55
Q

metasis

A

when cells from a malignant tumor spread from primary site

56
Q

cancer

A

a disease caused by uncontrolled cell division of abnormal cells

57
Q

mutagen

A

an agent that causes genetic mutation
ex: UV Radiation or chemicals

58
Q

carcinogen

A

substance capable of causing cancer

59
Q

describe why mutagens are not necessarily carcinogens

A

mutagens can change DNA structuree and carcinogens just affect uncontrolled cell division

60
Q

describe how cancer arises

A

cells become cancerous after mutations accumulate in the genes that control the cell cycle

61
Q

explain the relationships between oncogenes tumor suppressor genes and cancer

A

proto-onco genes are normal genes that code for proteins that help the cell move through the cell cycle, when proto-oncogenes are mutated, they become oncogenes that move the cell through the cell cycle even when it shouldn’t divide. there are tumor suppressor genes when cunvtion to stop a cell from dividing when it shouldn’t. tumor suppressors can mutate leading to the cell moving through the cycle when it shouldn’t. cancer develops when both types of genes are mutated and the cell divides without control.

62
Q

state the formula for calculation of miotic index

A

number of cells undergoing miotic index
over
total number of cells

63
Q

miotic index =
number of cells undergoing mitosis
—————————————-
total number of cells

A

expressed as a %
higher mitosis = growing faster
CANCER
tumors = uncontrolled cell division
mass of cells (tumor)

64
Q

primary tumors

A

occur at the site of the original cancerous cells

65
Q

metastasis

A

is the movement of those cells to other body regions
(secondary tumors)

66
Q

mutagens

A

things that can cause mutations

67
Q

carcinogens

A

mutagens that can cause cancer
- radiation
- viruses
- chemicals

68
Q

oncongenes

A

genes that have the potential to cause cancer

IB HL biology (12 decks)

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