Cell II Flashcards
What is the largest organelle in the cell?
Largest organelle in the cell
- ~10% cell volume
- DNA is sequestered in the nucleus
What are the components of the nucleus?
- Nuclear envelope
- Nuclear lamina
- Nuclear pores
- nucleolus
What are the parts of the nuclear envelope?
- inner nuclear envelope
- outer nuclear envelope
What is the function of inner nuclear membrane ?
- faces the nucleoplasm
- in contact with the nuclear lamina
What is the function of the outer nuclear envelope ?
- faces the cytoplasm
- Continuous with endoplasmic reticulum (ER)
- Cytoplasmic surface contains ribosomes
- Rough ER (rER)
Describe what is nuclear lamina
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
Where is the nuclear pore complex?
Spans the two nuclear membranes
- 80-100nm in diameter
How many proteins are in the nuclear pore complex? What type of proteins are they?
Made up of more than 50 proteins/ Nucleoporins
How much nucleopore complexes (NPCs) are in a typical nuclear envelope?
3000-4000 NPCs in a typical nuclear envelope
What is the function of the nuclear pore complex?
Allows transport of molecules between the nucleus and cytoplasm
What are the types of chromatin in the nucleus?
Euchromatin and heterochromatin
Differentiate euchromatin and heterochroatij
Euchromatin- less condensed, more transcriptionally active
Heterochromatin - condensed chromatin, lesss transcriptionally active
What 2 things are in the nucleus?
Chromatin and the nucleolus
What is the function of the nucleolus ?
Site of ribosome production
- ribosomal RNA is transcribed
- ribosomal subunits assembled
What are nucleosomes?
Fundamental structural unit of chromatin
Macromolecular complex
- 8 histone molecules (octamer)
- 2 loops of DNA wrap around the core octamer
- “beads on a string”
Where are nucleosomes found?
Found in both euchromatin and heterochromatin
List the events of the cell cycle
Interphase
- gap 1(G1)
- DNA synthesis (S)
- gap 2 (G2)
- Mitotic phase(M)
- Karyokenesis
- division of nucleus
- cytokinesis
- division of cytoplasm
Describe the events of somatic cell division: mitotsis
- interphase= DNA replicated
Mitotic phase
- Prophase
- early
- chromosome condensation
- mitotic spindle assembly
- late(prometaphase)
- Breakdown of nuclear envelope
- Spindle microtubules bund to kinetochores
- Metaphase- chromosomes align at metaphase
- Anaphase- sister chromatids separate
- Telophase
- sister chromatids arrive at opposite poles
- nuclear envelope reassembly
- nuclear division complete
- 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
List the events of reproductive cell division: meiosis
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
What is cancer ?
- 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
What is carcinoma?
- malignant tumor growing from epithelial tissue
- Many carcinomas affect glands that are involved with secretion
What is sarcoma?
- Malignant tumor growing from connective tissues
- cartilage, fat, muscle, tendons, and bones
- Ex. Osteosarcoma (bone) and chondrosarcoma
How much of human cancers are carcinomas?
~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
What are the neoplasm malignant behaviors?
- expansile and invasive growth; may mestastasise
- not encapsulated
