Cell II Flashcards

1
Q

What is the largest organelle in the cell?

A

Largest organelle in the cell

  • ~10% cell volume
  • DNA is sequestered in the nucleus
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2
Q

What are the components of the nucleus?

A
  • Nuclear envelope
  • Nuclear lamina
  • Nuclear pores
  • nucleolus
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3
Q

What are the parts of the nuclear envelope?

A
  • inner nuclear envelope

- outer nuclear envelope

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4
Q

What is the function of inner nuclear membrane ?

A
  • faces the nucleoplasm

- in contact with the nuclear lamina

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5
Q

What is the function of the outer nuclear envelope ?

A
  • faces the cytoplasm
  • Continuous with endoplasmic reticulum (ER)
  • Cytoplasmic surface contains ribosomes
    • Rough ER (rER)
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6
Q

Describe what is nuclear lamina

A

Thin, sheet-like meshwork beneath the inner nuclear membrane

  • Nuclear lamins
    • type of intermediate filaments
    • Lamina A & B
  • Scaffold for nuclear envelope, chromatin and nuclear pores
    • Disassembles during mitosis
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7
Q

Where is the nuclear pore complex?

A

Spans the two nuclear membranes

- 80-100nm in diameter

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8
Q

How many proteins are in the nuclear pore complex? What type of proteins are they?

A

Made up of more than 50 proteins/ Nucleoporins

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9
Q

How much nucleopore complexes (NPCs) are in a typical nuclear envelope?

A

3000-4000 NPCs in a typical nuclear envelope

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10
Q

What is the function of the nuclear pore complex?

A

Allows transport of molecules between the nucleus and cytoplasm

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11
Q

What are the types of chromatin in the nucleus?

A

Euchromatin and heterochromatin

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12
Q

Differentiate euchromatin and heterochroatij

A

Euchromatin- less condensed, more transcriptionally active

Heterochromatin - condensed chromatin, lesss transcriptionally active

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13
Q

What 2 things are in the nucleus?

A

Chromatin and the nucleolus

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14
Q

What is the function of the nucleolus ?

A

Site of ribosome production

  • ribosomal RNA is transcribed
  • ribosomal subunits assembled
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15
Q

What are nucleosomes?

A

Fundamental structural unit of chromatin

Macromolecular complex

  • 8 histone molecules (octamer)
  • 2 loops of DNA wrap around the core octamer
  • “beads on a string”
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16
Q

Where are nucleosomes found?

A

Found in both euchromatin and heterochromatin

17
Q

List the events of the cell cycle

A

Interphase

  • gap 1(G1)
  • DNA synthesis (S)
  • gap 2 (G2)
  • Mitotic phase(M)
  • Karyokenesis
    • division of nucleus
  • cytokinesis
    • division of cytoplasm
18
Q

Describe the events of somatic cell division: mitotsis

A
  • interphase= DNA replicated

Mitotic phase

  1. Prophase
    • early
    • chromosome condensation
    • mitotic spindle assembly
    • late(prometaphase)
    • Breakdown of nuclear envelope
    • Spindle microtubules bund to kinetochores
  2. Metaphase- chromosomes align at metaphase
  3. Anaphase- sister chromatids separate
  4. Telophase
    • sister chromatids arrive at opposite poles
    • nuclear envelope reassembly
      • nuclear division complete
  5. Cytokinesis
    - division of cytoplasm
    • contractile ring (cleavage furrow)
  • cell cycle completion
  • 2 genetically identical daughter cells
    • diploid (2n)
  • begins in late anaphase and end after Telophase
19
Q

List the events of reproductive cell division: meiosis

A

DNA is replicated
-2 x chromosomes (2n), 4 x sister chromatids (4d)

2 sequential nuclear divisions

Meiosis 1-Separation of homologous chromosomes

  • reduction division
    • Chromosome number reduced from 2n to 1n
    • DNA content reduced from 4d to 2d

Meiosis 2- Separation of sister chromatids

  • equatorial division
    • chromosome number unchanged 1n
    • DNA content reduced from 2d to 1d

-Each haploid gamete receives one complete set of 23 chromosomes

  • produces genetic diversity among gametes
    • crossing over and random assortment
  • Phases in the process of meiosis and similar to the phases of mitosis
    • Prophase,metaphase anaphase, Telophase
20
Q

What is cancer ?

A
  • Suffix “oma” means tumor or cancer
    • chomdra = tumor of cartilage tissue

-Cancer cells are classified according to tissue and cell type from which they originated

21
Q

What is carcinoma?

A
  • malignant tumor growing from epithelial tissue

- Many carcinomas affect glands that are involved with secretion

22
Q

What is sarcoma?

A
  • Malignant tumor growing from connective tissues
    • cartilage, fat, muscle, tendons, and bones
    • Ex. Osteosarcoma (bone) and chondrosarcoma
23
Q

How much of human cancers are carcinomas?

A

~90% of human cancers are carcinomas (epithelial origins)

  • Most of the cell proliferation in the body occurs in epithelia
  • Epithelial tissues frequently exposed to physical and chemical damage
24
Q

What are the neoplasm malignant behaviors?

A
  • expansile and invasive growth; may mestastasise

- not encapsulated

25
Q

What are the benign behaviors of neoplasm?

A
  • expansile growth only; grows locally

- often encapsulated

26
Q

What is the benign histology of neoplasm?

A
  • Resembles cell of origin (well differentiated)
  • Few mitosis
  • Normal or slight increase in ratio of nucleus to cytoplasm
  • Cells are uniform throughout the tumor
27
Q

What is the malignant histology of neoplasm?

A
  • May show failure of cellular differentiation
  • Many mitoses, some of which are abnormal forms
  • high nuclear to cytoplasmic ratio
  • Cells vary in shape and size (cellular pleomorphisms) and/or nuclei vary in shape and size (nuclear pleomorphisms)
28
Q

Describe metastasis

A

Malignant

  • Locally invasive
    • Tumor invades the tissues surrounding it by sending out “fingers” of cancerous cells into the normal tissue
  • Metastatic
    • Distant spread of the tumor cells into other tissu3s of the body
      • Vascular
      • Lymphatic
      • Transcoelomic
29
Q

What are Proto-oncogenes?

A
  • genes whose protein products regulate cell growth, proliferation and differentiation
  • normal regulatory molecules
30
Q

What are oncogenes?

A

-mutated proto-oncogenes

31
Q

What are tumor suppressor genes?

A
  • Genes that prevent unregulated cell cycle progression
  • Stimulates DNA repair or cause programmed cell death (apoptosis)
  • Loss of function mutations enhance susceptibility to cancer

E.g., p53

  • guardian of the genome
  • > 50% of human cancers show p53 mutations
32
Q

What do p53 and p21 do?

A

P53- DNA repair

P21- p21 inhibits cyclin and CDK resulting in cell cycle arrest