Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CTO2 - Cells to Organism > Growth > Flashcards

Growth Flashcards

1
Q

What is:
- anisotropy
- proportionality
- adaptability
- discontinuous scaling

A
  • anisotropy - direction-dependent nature of growth. different parts of a structure grow at different rates or in different directions.
  • proportionality - different parts of an organism or system grow in relation to each other to maintain overall balance and function.
  • adaptability - refers to an organism or system’s ability to adjust its growth in response to environmental changes or internal needs.
  • discontinuous scaling - refers to non-linear changes in size or shape as a system or organism grows. In some cases, growth may occur in sudden spurts rather than a steady, continuous manner.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the limits to cellular growth and what is the result of cells being too big?

A
  • transport
  • communication/coordination (time delay)
  • mRNA synthesis - maximum rate of transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 4 “tricks” to make big cells?

A
  1. vacuoles
  2. syncytia (skeletal cell stretched out, lots of nuclei so lots of cytoplasm)
  3. polytene chromosomes (lots of nuclei)
  4. helper cells - large oocyte has surrounding normal cells that delivers nutrient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What 2 factors are balanced during cell proliferation?

A

division and growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Outline the cell cycle

A

G1 - growth
S - DNA synthesis
G2 - growth and preparation of mitosis, checks for errors
M - mitosis cell division

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

cyclins work by controlling cyclin-dependent-kinases:
1. what is a kinase?
2. how does it regulate cell cycle

A
  1. phosphorylates other molecules
  2. each cdc only binds to specific cyclins. when it meets the right cyclin it will turn on and off proteins to push cells onto next cycle. always in cell but needs to meet specific cyclin to trigger response
    - creates feedback loop when one is active it creates condition to activate next one and inactive the one before
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which stage are there checkpoints and what do they check?

A

G2 check for DNA damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What causes the difference between well fed and less well fed cells?

A

well fed = more surface area facing outside to get nutrient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How are crystallising cells formed

A
  • side branches have higher SA so grows longer
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is hertwig’s rule?

A

(In the absence of over-riding factors) Cells orientate their division planes in the direction that will reduce mechanical stress in tissues. e.g. stretching ear piercing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does crowding cells orientate?

A
  • avoiding to make crowd worse
  • crowded = more patterned and oriented
  • sparse = ignores orientation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does Piezo1 link stretch or crowding to division decisions?

A

Piezo 1 transducing stress to calcium to mitosis, and Piezo 1 being in the membrane in tense cells and cytoplasm in crowded ones.

  • opens calcium channel when experiencing stress and tension, calcium comes in = mitosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does developing bird guts make loops

A
  • mesentery = thin membrane
  • gut tissue grows faster than mesentery but they remain attached
  • curve accommodates the faster growth of gut tissue relative to mesentery
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain how planar cell polarity is achieved on cell sheets

A
  • Within epithelium, there’s a different polarity (apical-basal vs. planar)
  • The south end is inactive.
  • The north end is active due to lack of inhibition.
  • Cell A signals to cell B which side is active, determining its north-south orientation. This, in turn, informs cell C of its directional activity.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give an example of how inhibition lines up and controls epithelium growth using polarity and direction

A

forming of neural tube (starting as a valley)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the foetal transfusion syndrome

A
  • risk of having an identical twin
  • two individuals - surrounding the same placenta
  • one twin can get more blood, more nutrients than the other
  • leads to different birth sizes (cardiovascular tissue)
16
Q

In terms of sizing of an organism, what is the relative difference in animals vs plants

A

animals have clear maximum size for a species, plants and fungi do not

17
Q

What is sexual dimorphism

A

Within a species, the two sexes can show marked differences in adult size

18
Q

What is a vitruvian man? Give examples of cases where vitruvian proportion is not shown

A

perfectly proportioned man by Leonardo da Vinci. e.g. gigantism or dwarfism

19
Q

In the case of gigantism, how did pituitary tumours affect growth?

A

pituitary gland secretes growth hormone which tells muscles to grow. overproduction or mutations in GH receptors

20
Q

What are GH signals often translated into ?

A

local signals of IGF 1 and 2

21
Q

Why are our 2 legs the same length? What happens when you restrict growth in one and what does it tell us?

A
  • Contralateral leg grows normally (-> lop-side bunny), no communication between the legs (didn’t wait for eachother)
  • Release the inhibition -> inhibited leg catches up (faster growth than the other).

The ability of the growth plate of the long bone to respond to GH declines with the number of cell divisions it has made. the more it has grown, the less able it is to grow with every division, concentration will divide and growth is diluted

  • growth plates are at the end of the bone and has several zones (proliferation with stem cell to maintain own number and create daughter cells that enlarge and turn into cartillage)
  • cartillage die but matrix picks up calcium. bone cells come in and displaces the dead cells
  • chain reaction asking different cell types to replace each layer allowing proliferation and growth
  • the bigger the bone is, the less efficient the signalling loops, slower it will grow
  • because small bone = growth plate closer to the edge
  • large bone = further away
22
Q

Achondroplasia = limbs are smaller but head and trunk are normal. How does FGF signalling work?

A

FGF signalling via FGFR3 usually inhibits both proliferation and differentiation of chondrocytes (it’s complicated). Activating mutations in FGFR3 cause growth plates full of chondrocytes, and premature closure of the growth plates

  • growth plates gets shut down earlier on
  • FGF tells signals its active when it isn’t due to mutation
23
Q

2 key points with Achondroplasia

A
  1. some parts of body keeps growing anyways
  2. amount of skin and tendon and muscle is correct for peculiar shortened limbs so tissue is not independent from eachother.
24
Q

3 Example of skin being in right proportion

A
  1. pregnancy
  2. male central obesity
  3. cultural practices
25
Q

In a plate, researcher grew cells. some corners were sharp and some were gentle. what is the difference in frequency of division?

A

stress is higher in sharp corners than gentle corners (spread out). high frequency where corners were sharp as they divide in an attempt to relieve the mechanical stress

26
Q

mechanical stress drives ___ of channels to increase ___

A

channels, division

26
Q

spleen in mouse: spleen extracted from mice and added lost of foetal spleens to see how big they would grow, result: each of the 9 grew to 1/9th of the size so total mass = mass of one normal spleen. what is the explanation

A

tissues release specific hormones called “chalones” which circulate and tissues detects chalone concentration coming back from the blood. too little = not enough tissue, correct amount of chalone = stops growing tissue.

27
Q

What is quorum sensing?

A

minimum number of cells needed to make something. once they reach a size they flip gene expression and differentiates

28
Q

How do cells know they’ve reached the right size for quorum sensing?

A
  1. cells have receptors for a factor that they themselves excrete
  2. so they detect the factor from themselves and also their neighbours
  3. local concentration of those secretions will rise due to : 1) more cells making it 2) crowd of cells reducing ability to diffuse away
  4. once enough of a signal, cell will make its response as it knows its in a big enough group
29
Q

Explain quorum sensing in the case of the kidney

A
  • these signals pushes mesenchyal cells and aggregates
  • when a big enough aggregate is formed, they switch their gene expression to pick up epithelial cells
  • as they make this, they switch on gene coding for Wnt4, they diffuse slowly
30
Q

What happens if Wnt4 is eliminated in nephron development forming aggregates?

A

no nephron. end up with large mass of mesenchyme because they are still waiting for signal to differentiate

31
Q

What happens to neurons in chicken embryo when one of the wings was removed vs graft wing attached onto diff chicken embryo

A
  1. fewer motor neurons when target field reduced
  2. more motor neurons when 2 wings on one side
32
Q

Time course of neuronal development.
1. 2 stages ___ and ____
2. cells make far _____neuron than it needs so lots of cells go through ____
3. T.D neurotrophic “independent” during ____ and dependent in ____

A
  1. mitosis & elective cell death
  2. too much & cell death
  3. mitosis & elective cell death
33
Q

What is T.D target derived?

A

they dont know how much they need but they continue dividing until maximus is reached, no target derived signals

34
Q

How does cell death depend on T.D neurotrophins?

A

competing for limited amount of T.D neurotrophins, so the ones that gets less will die and will keep happening until there’s enough neurotrophins to keep cell alive

35
Q

What Is the trophic theory?

A

generalised: beyond very early embryos, every cell depends its survival on survival factor secreted by different cells. keeps populations balanced (except in cancerous cells).

CTO2 - Cells to Organism (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions