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Biology > 2.1.6 Specialised cells and stem cells > Flashcards

2.1.6 Specialised cells and stem cells Flashcards

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1
Q

What are the levels of organisation of a multicellular organism in order?

A

1- organelle
2- specialised cells
3- tissues
4- organs
5- organ systems
6- whole organism

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2
Q

Define specialised

A
  • have specific structure for their specific function
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3
Q

Define differentiation

A

the process by which a cell becomes specialised for its function.

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4
Q

Define cell

A
  • the basic unit of life
  • consists of cellular contents and surrounded by a plasma membrane
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5
Q

Define tissue

A
  • a collection of differentiated cells that work together to perform a specialised function/functions
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6
Q

Define organ

A
  • a collection of tissues that work together to perform a particular function in an organism
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7
Q

Define organ system

A

a number of organs working together to carry out a major function in the body

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8
Q

Why do multicellular organisms have specialised cells?

A
  • cells do not have to compromise as they divide the labour and can be very effecient at a single job rather than stretched across many roles
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9
Q

How are erythrocytes specialised for their function?

A
  • transport oxygen around the body
  • flattened biconcave shape to increase SA:V
  • contain Hb to carry oxygen
  • no nuclei or many other organelles to have space for more Hb
  • flexible to squeeze through narrow capillaries
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10
Q

How are neutrophils specialised for their function?

A
  • type of white blood cell (phagocyte)
  • multi-lobed nucleus, easy to squeeze through small gaps and get to site of infection
  • granular cytoplasm containing many lysosomes (contain enzymes to attack pathogens)
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11
Q

How are sperm cells specialised for their function?

A
  • male gametes, deliver genetic info to female gametes
  • have tail/flagellum to move
  • have lots of mitochondria to supply energy to swim
  • acrosome on head of sperm contains digestive enzymes to digest protective layers around ovum
  • haploid nucleus to restore diploid number of chromosomes at fertilisation
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12
Q

How are palisade cells specialised for their function?

A
  • in mesophyll, contain chloroplast to absorb large amounts of light for photosynthesis
  • rectangular box shaped to pack closely to form continous layer
    -thin walls to increase rate of diffusion of CO2
  • large vacuole to maintain turgor pressure
  • chloroplast can move within cytoplasm to absorb more light
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13
Q

How are root hair cells specialised for their function?

A
  • long extensions present at surfaces of roots near growing tips
  • they increase SA of cell so maximise uptake of water and minerals from soil
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14
Q

How are guard cells specialised for their function?

A
  • pairs of guard cells found on surfaces of leaves that form small openings called stomata
  • openings for CO2 to enter plants for photosynthesis
  • cell wall thicker on one side so cell doesnt change shape symmetrically as its volume changes
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15
Q

How do guard cells prevent further water loss?

A
  • when guard cells lose water:
  • they become less swollen bc of osmotic forces
  • they change shape and stomata closes to prevent further water loss
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16
Q

What are the 4 main categories of tissues in animals?

A
  • epithelial tissue (body surfaces- internal+external)
  • nervous tissue (support transmission of electrical impulses
  • muscle tissue (adapted to contract)
  • connective tissue (adapted to hold other tissues together)
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17
Q

How are squamous epithelium specialised for their function?

A
  • v. thin tissue bc of flat cells that make it up and bc 1 cell thick
  • present when rapid diffusion across a surface is needed
  • forms lining of lungs and allows rapid diffusion of O2 into blood
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18
Q

How are ciliated epithelium specialised for their function?

A
  • have hair like structures (cilia) on surface that move in rhythmic manner
  • ciliated epithilium lines trachea (mucus swept away from lungs)
  • goblet cells present which release mucus to trap unwanted particles so stop them reaching alveoli
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19
Q

How is cartilage specialised for its function?

A
  • connective tissue in ear, nose, ends+between bones
  • contain fibres elastin and collagen
  • firm, flexible
  • prevents ends of bones from rubbing together and causing damage
20
Q

How is muscle specialised for its function?

A
  • contract to move bones/other contractile functions
  • different types of muscle fibres
  • skeletal muscle fibres (attatched to bone)
21
Q

How is epidermis tissue in plants specialised for its function?

A
  • single layer closely packed cells that cover surfaces of plants
  • covered by waxy, waterproof cuticle to reduce water loss
  • stomata (formed by pair of guard cells) present in epidermis and allow CO2 in water vapour, O2 out
22
Q

How is xylem tissue in plants specialised for its function?

A
  • vascular tissue
  • transport of water and minerals
  • composed of vessel elements (elongated dead cells)
  • walls are strengthened with waterproof material lingin (structural support)
23
Q

How is xylem tissue in plants specialised for its function?

A
  • vascular tissue
  • transport of water and minerals
  • composed of vessel elements (elongated dead cells)
  • walls are strengthened with waterproof material lingin (structural support)
24
Q

How is phloem tissue in plants specialised for its function?

A
  • vasuclar tissue
  • transport nutrients (e.g. sucrose) from where made (leaves and stems) to parts where needed
  • composed of sieve tube cells separated by perforated walls called sieve plates
25
Q

What are 3 examples of organ systems in animals and what are their functions?

A

1- digestive system - takes in food, breaks down large insoluble molecules into small soluble molecules, absorb nutrients into blood
2- cardiovascular system - moves blood around the body to provide transport system
3- gaseous exchange system - brings air into body so O2 used for respiration
4- nervous, 5- reproductive,

26
Q

Define stem cell

A
  • undifferentiated cells with the potential to differentiate into a variety of specialised cell types in the organism
27
Q

Define undifferentiated

A

an unspecialised cell that originates for mitosis/meiosis

28
Q

Define totipotent

A
  • a stem cell that can differentiate into any type of cell and form a whole organism
29
Q

Define pluripotent

A

a stem cell that can differentiate into any type of cell but not form a whole organism

30
Q

Define multipotent

A

a stem cell that can only differentiate into a range of cell types within a certain type of tissue

31
Q

Define embryonic stem cell

A

stem cell found in embryos
- totipotent and can differentiate into anything

32
Q

Define tissue/adult stem cell

A
  • found in bone marrow
  • can form cells of free living organism after birth
33
Q

Describe the characteristic abilities of stem cells. and compare with specialised cells

A
  • not been through (much) differentiation
  • can divide again and again producing many cells
  • specialised cells have specific tasks and don’t do cell cycle anymore as they have entered G0
34
Q

What is the importance of stem cells?

A

stem cells are a source for new cells necessary for growth, development and tissue repair

35
Q

Why must stem cell acitivity be carefully controlled?

A
  • if they do not divide fast enough they are not efficient for tissue repair=ageing
  • too fast/uncontrolled form masses/tumours which can lead to cancer development
36
Q

What are the 3 types of stem cells and where do they occur in animals?

A
  • totipotent - zygote
  • pluripotent - in embroys
  • multipotent - bone marrow
37
Q

Where in plants do stem cells occur and what type of potency do they have?

A
  • meristematic tissue (meristems)
  • found wherever growth is happening e.g. tips of roots and shoots
  • pluripotent
38
Q

How does a cell become specialised?

A
  • the stem cell cycles through the cell cycle doing mitosis
  • then enters G0 phase
  • commits to becoming certain type of cell
  • goes through series of changes to become suited for its role
39
Q

How are erythrocytes and neutrophils produced from stem cells in bone marrow?

dont know if i need to know this

A
  • nucleus ejected and Hb builds up for RBC
  • nucleus becomes lobed for neutrophil
40
Q

Why is it important for erythrocytes and neutrophils to be constantly produced?

A
  • RBC have short life span (120days) bc of lack of organelles and nucleus
  • neutrophils only live around 6 hours
  • production increases during infection
41
Q

How are xylem vessels and phloem sieve tubes produced from meristems?

A
  • meristem tissue producing xylem vessel+sieve tubes is vascular cambium
    1- cambium stem cells divide and some cells are pushed to centre of stem and some pushed to outer surface of stem
    2- (centre) they recieve molecular signals which trigger them to differentiate into xylem vessels
    3- (outer) receive molecular signals which trigger them to differentiate into sieve tube elements
    (some stem cells in cambium stay in cambium and stay undifferentiated to produce more xylem vessles and sieve tube elements)
42
Q

What are 7 diseases that stem cells have the **potential **to treat?
- describe how stem cells may be useful

A

1- heart disease - (StemC transplanted to replace irreparably damaged muscle)
2 - type 1 diabetes - (when own immune system destroys insulin producing cells, StemC can replace them)
3 - parkinsons diease - (shaking+rigidity bc of death of dopamine producing cells in brain, StemC can replace dead cells)
4 - Alzheimers disease - brain cells destoyed by build of up abnormal proteins
5 - macular degeneration - cause blindless in elderly and diabetics
6 - birth defects
7 - spinal injuries

43
Q

How stem cells might be useful in treating burns

A
  • stem cells grown on biodegredable meshes produce new skin for burn patients
44
Q

What are 2 ways in which stem cells might be useful in research?

A

1 - used in drug trials - test new drugs on cultures of stem cells before animal/human testing
2 - developmental biology - how differentiation process works to form mutlicellular organisms and how it sometimes goes wrong

45
Q

What are the arguments for the use of embryonic stem cells for research and medicine?

A
  • spare embryos from IVF would of been destroyed anyway
  • relieves suffering if treatment found
  • transplantation organs in short supply
46
Q

What are arguements against the use of embryonic stem cells for research and medicine?

A
  • stem cells from human embryos so amounts to killing/murder unborn child
  • parents of spare embryos might reject
  • infection risks when transferring
  • religious objections bc of rights of embryo
  • ignores embryo rights
47
Q

Define induced pluripotent stem cell and why they may be useful in research and medicine.

A

IPSC - adult stem cells that have been genetically modified to act like embryonic stem cells
- bc doesnt raise same ethical issues as embryo
- genetically identical to patient so no rejection risk

Biology (32 decks)

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