Nucleus, Chromatin, Nucleolus Flashcards

1
Q

What are the major regions of the cell?

A

cytoplasm + nucleus = protoplasm

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2
Q

What are the functions of the nucleus?

A
  1. stores genetic information of the cell
  2. where DNA is transcribed
  3. where chromosomes are localized
  4. where chromosomes are replicated
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3
Q

What are the structural components of the nucleus?

A

nuclear envelope, nuclear pores, nucleoplasm, nucleolus, chromatin, nuclear skeleton

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4
Q

What lines the inner nuclear membrane?

A

nuclear lamina

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5
Q

What is the function of the nuclear lamina?

A
  1. stabilize nuclear envelope
  2. support chromatin - acts as an attachment site for chromatin
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6
Q

What is the structure of the nuclear envelope?

A

outer membrane and inner membrane with perinuclear space between them

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7
Q

What is the outer membrane and perinuclear space of the nucleus continuous with?

A

rough endoplasmic reticulum

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8
Q

What is the function of nuclear pores of nuclear envelope?

A

controls movement of substances into and out of the nucleus

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9
Q

What is the nuclear pore complex?

A

proteins attached to the nuclear pore + nuclear pore e.g. nucleoporins

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10
Q

What is transported out of the nucleus and what is transported in?

A

RNA and ribosomal subunits needed for protein synthesis are transported out and proteins are transported in

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11
Q

What is the function of nuclear matrix?

A
  1. keep cell shape
  2. support chromatin fibers
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12
Q

What is responsible for the basophilic characteristic of the nucleus?

A

chromatin

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13
Q

What is chromatin?

A

long strand of DNA and associated proteins in an uncoiled state

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14
Q

What are the types of chromatin?

A

euchromatin and heterochromatin

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15
Q

What is Euchromatin?

A

light, loosely packed, active - light staining material

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16
Q

What is Heterochromatin?

A

dense, tightly packed, inactive - dark staining material

17
Q

What are the 3 locations for heterochromatin?

A
  1. peripheral of the nucleus
  2. karyosomes
  3. near nucleolus
18
Q

What is facultative heterochromatin?

A

chromosome material that can either be heterochromatin or euchromatin e.g. inactive X chromosome

19
Q

What is constitutive heterochromatin?

A

chromosome material that can only be heterochromatin e.g. Y chromosome

20
Q

What are chromosomes?

A

long molecule of DNA and associated proteins that carry hereditary information that has been tightly packed (condensed) and replicated forming 2 sister chromatids that are held together by cohesions

21
Q

What is the structure of chromosomes?

A

two sister chromatids connected at the centromere

22
Q

Types of chromosomes?

A
  1. metacentric - centromere is in the middle
  2. submetacentric - centromere is between middle and end
  3. acrocentric - the centromere is placed close to the end
  4. telocentric - centromere is placed at the end
23
Q

How are these types of chromosomes developed?

A

centromere is placed at different points on the chromosome

24
Q

Describe the shorter arm?

A

is always placed above the centromere - the p arm (petite)

25
Describe the longer arm?
is always placed below the centromere - the q arm
26
How are chromosomes characterized?
1. length 2. position of the centromere 3. banding pattern
27
Ends of the chromosome are called?
telomeres
28
What are nucleosomes?
chromatin fundamental unit - strand of DNA wrapped around 8 histones twice
29
What are the 43 chromosomes in a human being?
22 pairs of autosomal chromosomes and 1 pair of sex chromosomes
30
What are karyotypes?
chromosome pairs sorted according to their morphology
31
What is a Barr body?
dense mass of heterochromatin present in females but not males - inactivated X chromosome
32
What can Barr bodies be used to identify?
sex of the fetus
33
What is the nucleolus?
condensed component of eukaryotic cells - basophilic
34
What makes up the nucleolus network?
pars fibrosa + pars granulosa = nucleolonema
35
What are 3 functions of the nucleolus?
1. site for initial ribosomal assembly 2. RNA synthesis 3. contains DNA, RNA and proteins