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Biology SL > 1.1 Cell Introduction > Flashcards

1.1 Cell Introduction Flashcards

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1
Q

what are the principles of cell theory? (3)

A
  1. all living things are composed of cells
  2. the cell is the smallest unit of life
  3. cells only arise from pre-existing cells
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2
Q

what are the 3 caveats to the cell theory?

A
  • striated muscle fibres
  • aseptate fungal hyphae
  • giant algae
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3
Q

why is striated muscle fibre a caveat to cell theory? (2)

A
  • muscle cells fuse to form fibres that may be very long
  • they have multiple nuclei despite being surrounded by a single, continuous plasma membrane
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4
Q

how do striated muscles cells challenge the cell theory?

A

challenge the idea that cells always function as autonomous unit

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5
Q

why is aseptate fungal hyphae a caveat to cell theory? (2)

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 continuous cytoplasm along the length of the hyphae
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6
Q

how do aseptate fungal hyphae challenge the cell theory?

A

challenge the idea that living structures are composed of discrete cells

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7
Q

why is giant algae a caveat to cell theory?

A

they may grow very large

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8
Q

how do giant algae challenge cell theory?

A

challenge that large organisms are always made of many microscopic cells

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9
Q

what are 7 basic functions integral to survival?

A
  • metabolism- living things undertake essential chemical reactions
  • reproduction - living things produce offspring (sexually/asexually)
  • sensitivity - living things are responsive to internal and external stimuli
  • homeostasis - living things maintain a stable internal environment
  • excretion - living things exhibit the removal of waste products
  • nutrition - living things exchange materials and gases w/ environment
  • growth - living things can move and change shape or size
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10
Q

why must unicellular organisms carry out all functions of life?

A

they are composed of a single cell

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11
Q

what are 2 examples of unicellular organisms?

A

paramecium
scenedesmus

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12
Q

how does paramecium carry out all of its cell functions? (6)

A
  • surrounded by small hairs called cilia allow it to move (responsiveness)
  • engulf food via specialised membranous feeding groove called a cytostome (nutrition)
  • food particles are enclosed within small vacuole that contain enzymes for digestion (metabolism)
  • solid wastes are removed via anal pore, liquid waste is pumped out via contractile vacuoles (excretion)
  • essential gases enter and exit via diffusion (homeostasis)
  • divide asexually (fission) although horizontal gene transfer can occur via conjugation (reproduction)
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13
Q

how does scedesmus carry out all of its cell functions? (4)

A
  • exchange gases and other essential materials vis diffusion (nutrition/excretion)
  • chlorophyll pigments allow organic molecules to be produced via photosynthesis (metabolism)
  • daughter cells form as non-motile autospores via internal asexual division of the parent cells (reproduction)
  • scedesmus may exist as unicells/ form colonies for protection (responsive)
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14
Q

how is the rate of metabolism of a cell found?

A

mass/volume (larger cells need more energy to sustain essential functions)

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15
Q

how does the rate of material exchange found?

A

surface area (large membrane surface equates to more material movement)

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16
Q

How does how cell growth influence the SA:VOL ratio?

A

as the cell grows, volume increases faster than surface area, leading to a decreased SA:VOL ratio

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17
Q

what will occur if the metabolic rate exceeds the rate of exchange of vital materials and wastes and the consequence? (2)

A
  • the cell will eventually die
  • growing cells tend to divide and remain small in order to maintain a high SA:VOL ratio suitable for survival
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18
Q

what are two types of cells or tissues that are specialised for gas/ material exchange will increase their surface area to optimise material transfer?

A

vili
alveoli

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19
Q

how do villi specialise to increase their surface area to optimise material transfer?

A
  • have ruffled structures to increase the surface area of the inner lining
20
Q

how do alveoli specialise to increase their surface area to optimise material transfer?

A
  • microvilli -> membranous extension which increases the total membrane surface
21
Q

how do you calculate magnification/actual size/ image size?

A

I = AxM

22
Q

what are advantages of light microscopes? (3)

A
  • viewed in natural colour
  • cheap
  • easy to access
23
Q

how do emergent properties arise?

A

when the interaction of individual component produce new functions

24
Q

why can multicellular organisms complete functions that unicellular organisms can’t

A

due to the collective actions of individual cells combining to create new synergistic effects

25
Q

what is the order of multicellular organisms?

A

cells grouped to form tissues
multiple tissues to form organs
organs that interact form organ systems
organ systems that collectively carry out life functions of complete organism

26
Q

what is differentiation?

A

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

27
Q

what do all organisms share?

A

share identical genome

28
Q

what causes differentiation to occur>

A

the activation of different genes within a given cell by chemical signals

29
Q

what is DNA packaged with to form chromatin?

A

proteins

30
Q

what are active genes usually packaged in which is accessible to transcriptional machinery?

A

euchromatin

31
Q

what are inactive genes are typically packaged in a more condensed form?

A

heterochromatin (saves space, not transcribed)

32
Q

how will different regions of DNA packaged as euchromatin and heterochromatin?

A

according to their specific function

33
Q

what 2 key qualities do unspecialised cells have?

A
  • self-renewal (can continuously divide and replicate)
  • potency (can differentiate into specialised cell types)
34
Q

what are the 4 types of stem cells?

A
  • totipotent - form any cell type and extra-embryonic (placental) tissue (eg. zygote)
  • pluripotent - can form any cell type (eg. embryonic stem cells)
  • multipotent - can differentiate into a number of closely related cell types (eg. haematopoetic adult stem cells)
  • unipotent - cannot differentiate but not capable of self-renewal (eg. progenitor cells, muscle stem cells)
35
Q

why can stem cells be used for viable therapeutic options?

A

cells that are not capable of self-renewal cannot be regenerated or replaced when these tissues become damaged, stem cells can be used

36
Q

what is the process of stem cell used to replace damaged or diseased cells with healthy functioning ones? (4)

A
  • use of biochemical solutions to trigger the differentiation of stem cells into desired cell type
  • surgical implantation of cells into the patient’s own tissues
  • 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
37
Q

what are 3 examples of stem cell therapy?

A

stargardt’s disease
parkinson’s disease
leukemia
paraplegia
diabetes
burn victims

38
Q

what is stargardt’s disease and how can stem cells be used?(3)

A
  • inherited juvenile macular degeneration cause vision loss to the point of blindness
  • caused by gene muation that imparis energy transport in retinal photoreceptor
  • treated by replacing dead cells in retina w/ functioning ones derived from stem cells
39
Q

what is parkinson’s disease and how can stem cells be used?(3)

A
  • a degenerative disorder of CNS caused by death of dopamine-secreting cells in midbrain
  • dopamine= neurotransmitter responsible for transmitting signals
  • treated by replacing dead nerve cells with living, dopamine-producing ones
40
Q

what are 4 other therapeutic examples and how they can be treated? (4)

A
  • leukemia - bone marrow transplant for cancer patients who are immunocompromised as a result of chemotherapy
  • paraplegia - repair damage caused by spinal injuries to enable paralysed victims to regain movement
  • diabetes - replace non-functioning islet cells w/ those capable of producing insulin in type I diabetics
  • burn victims - graft new skin cells to replace damaged tissues
41
Q

what 3 things placed stem cells be derived from?

A

embryos (may be specially created by therapeutic cloning)
umbilical cord blood/ placenta or newborn babies
certain adult tissues like bone marrow (not pluripotent)

42
Q

what are ethical considerations associated w/ therapeutic use of stem cells of the source? (3)

A
  • using multipotent adult tissues may be effective for certain conditions but limited in its scope of application
  • stem cells derived from umbilical cord blood need to be stored and preserved at cost, raising issues of availability and access
  • greatest yield of pluripotent stem cells come from embryos but requires destruction of potential living organism
43
Q

what are 2 artificial stem cell techniques?

A

somatic cell nuclear transfer (SCNT)
nuclear reprogramming

44
Q

what is somatic cell nuclear transfer (SCNT)?(2)

A
  • involves the creating of embryonic clones by fusing a diploid nucleus w/ enucleated egg cells (therapeutic cloning)
  • more embryos are created by the process, raising ethical concerns about exigency of excess embryos
45
Q

what is nuclear reprogramming? (2)

A
  • induce a change in the gene expression profile of a cell in order to transform it into a different cell type (transdifferentiation)
  • involves the use of oncogenic retroviruses and transgenes, increasing the risk of health consequences

Biology SL (38 decks)

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