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Biology HL > 1.1 introduction to cells > Flashcards

1.1 introduction to cells Flashcards

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1
Q

Cell Theory

A

All living things are composed of cells
cells are the smallest unit of life
all cells arise through preexisting cells

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2
Q

All living things are composed of cells

A

cells can be multicellular like a bat, or unicellular like bacteria

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3
Q

Cells are the smallest unit of life

A

specialized organisms within cells called organelles carry out specific functions

organelles can not survive on their own (paramecium)

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4
Q

All cells arise through preexisting cells

A

cells multiply through division
all life evolved from simpler ancestors
mitosis results in genetically identical diploid daughter cells
meioses generates in haploid gametes (sex cells)

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5
Q

First thing that disproves cell theory

A
  • striated muscle goes against the idea that a cell can only have one nucleus
  • striated muscle cells are multi nucleated
  • they have a single plasma membrane but more than one nucleus
  • striated muscles called fibres can be very long (300 mm)
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6
Q

Second thing that disproves cell theory

A
  • aseptate fungal hyphae challenges the idea that a cell is a single unit
  • it has a continuous cytoplasm and is multi nucleated
  • it is very large
  • The cytoplasm is continuous along the hyphae and has no end cell wall or membrane
  • cell wall is made of chitin
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7
Q

Third thing that disproves cell theory

A
  • acetabularia challenges the idea that cells have to be simple in structure and small in size
  • it is very big (5-100mm)
  • it has a complex structure: bottom rhizoid, long stalk, umbrella cap
  • bottom rhizoid contains the nucleus
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8
Q

functions of life

A

metabolism- the web of all enzyme catalysed reactions that occur within a cell or organism

response- organisms can react to the environmental

Homeostasis- the regulation of internal cell conditions (ph and water)

Growth- living things can grow and change in size/shape

Reproduction- all organisms produce offspring- asexual or sexual

Excretion- the removal of metabolic waste

Nutrition- feeding through the synthesis of organic molecules (photosynthesis) or through the absorption of organic matter

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9
Q

Function of life seen in paramecium

A

Metabolism - most metabolic reactions occur in the cytoplasm

Response- cilia sways to move the paramecium in response to a change in environment

Homeostasis- contractile vacuole holds water and excretes it through cell membrane

Growth- Cell will continue to gain and assimilate biomass until division

Reproduction- the nucleus is able to divide into to two to support division through mitosis- asexual

Excretion- metabolic waste is excreted via the plasma membrane

Nutrition- food vacuoles carry organisms ingested by paramecium

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10
Q

Surface Area and Volume- why do we want to maximise it

A

Maximising surface area - volume ratio increases efficiency of cell. This is because an area measured by volume needs to excrete and obtain essential nutrients, and has more surface area/membrane to serve it.

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11
Q

where do most metabolic reactions occur

A

membrane-compartmentalizing

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12
Q

Surface Area / Volume importance

+ the exception

A

Increasing this ratio decreases the path for diffusion, making movements in and out of the cell faster and less time consuming, as well as in the case of active transport, less energy consuming. This also helps generate concentration gradients.

However, the exception is warm-blooded mammals, where this causes them to lose heat quickly. Desert plants also need less surface area to maintain water.

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13
Q

Description of surface area and volume affecting cell life as it grows

A
  • The rate of Metabolic reactions in a cell is a function of its mass/ volume
  • The rate of material exchange in and out of the cell is a function of its surface area
  • As a cell grows, its volume increases faster than its surface area
  • if a cell has a faster rate of metabolic reaction than material exchange, it will eveuntually die
  • because of this, cells have to divide to maintain a suffiecent surface area/volume ratio
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14
Q

Example of surface area

A
  • Intestines are folded over to increase surface area and absorb more food particles
  • alveoli in the lungs is a thin membrane to increase surface area for gas exchange
  • Cells and tissues specilized for gas or material exchange will increase their surface area to optimise the transfer of materials (microvilli in the small intestine)
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15
Q

e_____ properties

A
  • emergent properties arise from the interaction of its component parts
  • The whole is bigger then the sum of its parts
  • multicellular organisms carry out more functions than an individual cell because of the interactions between the cells.
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16
Q

gene expression in cells

A
  • Diploid cells in organisms share an identical genome
  • cells carry all the genetic code of an organism
  • not all genes are expressed in all cells
  • totipotent embryonic stem cells express the whole genome
  • newly formed cells are sent signal to turn off genes- skin cells do not need to produce haemoglobin (a pigment in red blood cells that carries oxygen)
  • as a result of gene expression differentiation, the cells metabolism and shape changes in order to carry out a specialized function
17
Q

active and inactive genes

A
  • Active genes are packed expanded and reachable in euchromatin
  • inactive genes are packed condensely in heterochromatin
  • the less active genes a cell has, the more specialized its function.
18
Q

Specialized genes in humans

A
  • humans have 220 highly specialized cells
  • all specialized cells and the organs constructed from them have developed as a result of differentiation
  • example: blood cells, bone cells, cardiac muscle cells
19
Q

Stages of stem cells

A

totipotent- can differentiate into any type of cell

  • pluripotent- can differentiate into most types of cells
  • multipotent- can differentiate into a few closely related types cells
  • unipotent- can regenerate but can only differentiate into their associated cell type
20
Q

stargdts dieasise

A
  • affects 1 in 10,000 children
  • it is a recessive genetic condition
  • mutation causes an active transport protein on photoreceptor cells are dysfunctional
  • dysfunctional proteins can not transport energy
  • this causes the photoreceptor cells to degenerate
  • progressive, but eventual total loss of central vision.

solutions:

  • embryonic stems cells are divided and differentiated to become specialized retina cells
  • the retina cells are injected into the retina
  • they attach to the retina and become functional
21
Q

leukaemia

A

cancer of blood or bone marrow which leads to an excessive amount of poorly functioning white blood cells

solutions:

  • Hsc’s are taken from bone marrow, peripheral blood, or umbilical cord.
  • radiotherapy and chemotherapy are used to kill the dysfunctional white blood cells
  • the dysfunctional white blood cells have ot be replaced with healthy white blood cells
  • Hsc’s are transplanted into the bone marrow where they can differentiate and produce new healthy white blood cells.
22
Q

Pros to use of embryonic stem cells

A
  • stem cell research can pave the way to new discoveries and new technologies that wouldn’t have happened if it was banned
  • stem cell research can cure diseases or disabilities with cell therapy
  • transplants are less likely to be rejected since they are genetically identical to the patient
  • transplants do not require the death of another human
  • embryos that have stopped developing and would’ve died anyways can be used
  • embryos have no nervous system and can arguably feel no pain
  • induced pluripotent stem cells- embryos don’t have to be fertilized
23
Q

Cons to use of embryonic stem cells

A
  • involves the creation and destruction of a human embryo
  • embryo can continuously divide and lead to cancerous tumor growth
  • more embryos are produced than needed, so excess embryos are killed
  • with additional fund and effort, alternative technology can provide the same results
  • moral/religious disagreement with ‘playing god’
  • embryo can be placed in an IVF and would potentially develop
  • some race may genetically clone the first human.
24
Q

Describe the use of embryos for stem cells:

A
  • can be retrieved from excess embryos generated in Ivf programs
  • includes the creation and destruction of a human embryo
  • Unlimited growth
  • can lead to tumors
  • can differentiate into any cell
  • less genetic damage
  • not genetically identical to patient
25
Q

Describe the use of umbilical cord for stem cells:

A
  • limited quantities can easily be retrieved and stored from the umbilical cord
  • cord would have been discarded regardless
  • limited growth
  • less likely to form tumors
  • can differentiate into a few types of cells (unless induced can only divide into blood cells)
  • less genetic damage
  • genetically identical to patient
26
Q

Describe the use of humans for stem cells:

A
  • Difficult to retrieve as stem cells are buried deep in tissues
  • Human can consent
  • limited growth
  • less likely to form tumors
  • can differentiate into a limited number of cells (depending on what tissue was used)
  • more genetic damage due to gentic mutations that occured over time
  • genetically identical to patient.
27
Q

Contrast the structure of a plant and animal cell

A
  • large central vacoule vs no/small vacuole
  • chloroplast vs no chloroplast
  • cell wall vs no cell wall
28
Q
  • as a result of gene expression differentiation,
A
  • as a result of gene expression differentiation, the cells metabolism and shape changes in order to carry out a specialized function

Biology HL (26 decks)

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