Lecture 5 Flashcards

junctional complexes and cell cycle

1
Q

different junctions starting from the topmost type

A
  • zonula occludens
  • zonula adherens
  • macula adherens (desmosomes)
  • gap junction
  • hemidesmosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what makes up the zonula Occludens?

A

membrane proteins: Occludins and claudin, whihc comme together to make homo-dimers that hold the cells together
cytoplasmic proteins: ZO-1, actin

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

what is another name for zonula occludens?

A

tight junctions

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

what makes up Zonula Adherens?

A

membrane proteins: Cadherins
cytoplasmic: a-actinin, vinculin, actin

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

what is the intercellular space between cells in zonula adherens?

A

15 nm

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

what is another name for macula adherens?

A

desmosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what makes up macula adherens?

A

intercellular space contains TM proteins Desmocollin and Desmoglein.
Plaque contains desmoplakins I and II, Plakoglobin, and desmocalmin
Intermediate filaments: keratin (no polarity)

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

what is the intercellular space between cells attached via macula adherens?

A

25 nm

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

what makes up hemidesmosomes?

A

plaque: BP 200
TM proteins: integrins (a6b4) and BP 180
intermediate filaments: tonofilaments

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

what makes up gap junctions?

A

6 connexins, which make a connexon, attaches to another connexon from the other cell to make a channel that is 1.5 nm in diameter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

intercellular space between gap junction?

A

2 nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

when talking about stem cells, what does steady state mean?

A

of newly originated cells by the stem cell are equal to the # of dead cells on the surface of the epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is turnover time?

A

the time required to change the whole population of epithelial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the turnover time of skin

A

30 days

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

what is radioautography and how does it work?

A
  • provides a means to study the turnover of epithelial cells and of other cell types
  • works by adding radiated Thymidine (H3-T), then using photographic development which will allow us to see a black dot where the DNA is radioactive
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the purpose of cell division?

A

During embryogenesis and postnatal development, for growth.
During adulthood, to maintain tissue.

17
Q

what are the 3 ways cells/tissues behave in adulthood?

A

static (e.g. neurons and skeletal muscle)
Expanding (e.g. liver)
Renewing (e.g. epidermis)

18
Q

how many chromosomes (and pairs) do humans have?

A

23 pairs, so 46 total

19
Q

what are the phases of the cell cycle? how long is each?

A

G1: presynthesis of DNA; 25 hours – 2n
S: synthesis of DNA; 8 hours
G2: post DNA duplication; 3 hours – 4n
Mitosis: 2.5 hours – 2n

20
Q

what are the stages of mitosis?

A
  1. preprophase: intranuclear condensation of chromosomes
  2. prophase: visualization of chromosomes and mitotic spindle
  3. metaphase: chromosomes in equatorial plane and loss of nuclear envelope/nucleolus
  4. early anaphase: longitudinal splitting of chromosomes
  5. late anaphase: migration of chromosomes to the poles
  6. telophase: nuclear restitution, nuclear envelop and nucleolus formation