Exam 1: Cytology and Gametogenesis Flashcards
Cytology
Study of anatomy, physiology, pathology, and chemistry of the cell
Cytosol
Medium inside limits of cells
Where organelles are located
Cytoplasm - everything within a cell –> cytosol + organelles
Plasma membrane - limits
Cells
•exomembrane
Organelles and nucleus
•endomembrane
Mitochondrial core
•internal (mitochondrial) membrane
Plasma membrane - chemistry
Proteins - structural or involved in signaling, transportation
Lipids - mainly phospholipids and others (cholesterol)
Hydrocarbons - mainly and proteins (surface glycoproteins)
Glycolipids, glycoproteins, etc.
Plasma membrane - fluid mosaic
J. Singer and G. Nicolson
Gives membrane fluid character
Several types of molecules that are constantly moving
Movement helps membrane maintain role as barrier for cell
Plasma membrane - microvilli
Apical border, brush border
Extends and increases surface area of membrane to increase absorption
Ex - small intestine mucosal cells
Plasma membrane - glycocalyx
Helps with cell recognition
Keeping cells from sticking to lumen
Ex - endothelium
Plasma membrane - intermembranous junctions
Places where two cells attach very firmly or loosely to each other
Ex - epidermal cell desmosomes
•Desmosomes have tight junctions
Mitochondria
Important for energy production - “engine” of the cell
Autonomous division (fission) - can replicate on own
Absent in prokaryote cells (no nucleus)
Mitochondria structure
Outer smooth membrane
Matrix
•Fluid in the mitochondria
•Krebs cycle takes place in matrix
Inner rough membrane - crests
•Globular units - crests
•Oxidative phosphorylation takes place in crests
Mitochondria functions (3)
Oxidative phosphorylation
•ADP to ATP
•Takes place in crests
Respiratory chain
•Takes place in crests
Krebs cycle
•Takes place in matrix
Rough Endoplasmic Reticulum
In cytosol
Surface covered with ribosomes
Forms nuclear membrane
Ribosomes
Ribonucleic acid + protein
Subunits 40s and 60s
Ribosomes on RER produce proteins for export out of cell
Ribosomes in cytosol produce proteins for internal cell use
Smooth Endoplasmic Reticulum
Surface lacks ribosomes
Produces enzymes for lipid synthesis and metabolism
•Steroid hormone synthesis
•Glycogen metabolism
Produces fat and sugars
Golgi apparatus
Connects ER and cell membrane
Stores produce from RER and SER
Produces polysaccharides
Forms zymogen granules and other vesicles to export Golgi, RER, and SER products
•Granules merge with cell membrane
•Contents extruded - exocytosis
Golgi - protein metabolism
RER –> Golgi –> Membrane
Golgi - lysosome formation
Golgi forms lysosomes
Lysosomes full of enzymes for digestion
•Proteinases, lipases, phosphatases
Lysosomes
Can stay in cytosol to protect cell from something by excreting it out
Can stay in cytosol to digest things cell doesn’t need at the moment to be recycled
Numerous in immune system cells - neutrophils, NK cells, etc.
Numerous in renal tubular epithelium
Toluidine blue can be used to mark lysosomes
Cytoskeleton - functions
Structure - scaffolding of cell
Transport of materials through cell via microtubules
Movement
Cytoskeleton - Microtubules
Tubulin protein
Tubulins are dimers - a and B
Cytoskeleton - centriole
Cell reproduction
Mitotic spindle
Base for cilia and flagella
•Centriole forms anchor for cilia and flagella
Cytoskeleton - Microfilaments
Intermediate filaments
Actin, myosin, vimentin, cytokeratin
Nucleus - composition
Membrane
Chromatin
Nucleolus
Nucleus - Functions
Regulates protein synthesis
Contains and transfers genome
Nucleus - membrane (envelope)
Double, formed by specialized portion of RER
Covered with ribosomes
Selective permeability
Disappears during cell division
Nucleus - Chromatin
DNA + proteins (histones)
Types:
•Euchromatin - dispersed and in use (EC)
•Heterochromatin - condensed, not in constant use (HC)
Cell division, shape change - chromosomes
Nucleus - nucleolus
Site of assembly for ribosomal RNA
•rRNA + proteins = ribosome
Ribosomes migrate to cytosol through nuclear pores
Nucleolus disappears during parts of cell division
Largest nucleoli present in fast growing cells and reproductive cells
Cell cycle
G1 S - DNA replication G2 M phase - mitosis G0 - permanent withdrawal from cell cycle to differentiate
Cell division - M phase
Prophase
Metaphase
Anaphase
Telophase
Mitosis - prophase
Nuclear membrane dissolves
Nucleolus disappears
Chromatin form chromosomes with 2 chromatids
Centrioles duplicate and migrate to poles
Mitotic (microtubule) spindle begins to form
Mitosis - metaphase
Chromosomes pair up at the center
Mitotic spindle is complete
•Centriole to centriole
•Centriole to kinetochore (in chromosomes)
Mitosis - anaphase
Centrioles pull on mitotic spindle
Chromosomes split on long axis and migrate to poles
Mitosis - telophase
Chromosomes are at the poles
Nuclear membrane reforms
Mitotic spindle disappears
Cell splits in two diploid daughter cells
Meiosis
Gametes
Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II
Meiosis - Prophase I
Chromosomes with 2 chromatids - crossover
•Non-sister chromatids exchange segments (chiasma)
Nuclear membrane disappears
Centrioles and spindle form
Meiosis - Metaphase I
Chromosomes align in center, attached to spindle
Each of a pair attached to only 1 fiber of the spindle
Meiosis - Anaphase I
Spindles contract
Whole chromosomes (with 2 chromatids) migrate to poles
Each member of a homologous pair goes to a different pole
Meiosis - Telophase I
Chromosomes at poles
Nuclear membrane begins to form
Mitotic spindle disappears
Cells separate - 2 diploid daughter cells
Meiosis - Prophase II
Chromosomes condense - haploid (n)
Nuclear membrane disappears
Mitotic spindle forms
Meiosis - Metaphase II
Chromosomes align along the center (equator)
Mitotic spindle is fully formed
Each chromosomes in attached to 2 fibers of the spindle, at the centromere
Meiosis - Anaphase II
Mitotic spindle retracts
Chromosomes split in half at centromere and migrate to poles
Meiosis - Telophase II
Nuclear membrane forms, spindle disappears, cells separate
Haploid daughter cells - gametes
Gametogenesis
Development of gametes
Spermatogenesis
Oogenesis
Spermatogenesis
Begins with sexual maturity
Undifferentiated epithelium into Sertoli cells - scaffolding and nurturing of sperm cells
Stem cells divide (mitosis) - A and B spermatogonia
•A goes back to mitosis
•B goes through mitosis once then meiosis - does not reenter stem cell replenishing program
Spermatogonia B
- Divide by mitosis
- Primary spermatocytes divide by meiosis I
- Secondary spermatocytes divide by meiosis II
- Get spermatids
End of spermatogenesis proper - morphologic changes follow
Spermatogenesis - morphologic changes
Nucleus condenses in head
Golgi’s acrosomal granules surround nucleus
•Golgi migrates to top and becomes a “helmet” –> acrosome
Centrioles to mid-piece - base of flagellum (tail)
Mitochondria surround centrioles
Cytosol and other organelles removed in residual body
Spermatozoa - head
Condensed nucleus (haploid)
Acrosome with enzymes
•Hyaluronidase and cathepsin - break through ovum’s corona radiata
Spermatozoa - Neck
Centrioles - flagellum base
•Composed of 9 triplets of microtubules
Mitochondria - energy providers
Spermatozoa - tail
9 pairs of microtubules and 1 central pair
Oogenesis - in utero
- Oogonia in ovarian cortex (Diploid)
- Oogonia divide by mitosis - some die by autolysis
- Oogonia differentiate - 1a oocytes (diploid)
- Squamous cell surround 1a oocytes - primordial follicle
- 1a oocytes begin division (meiosis I, prophase I)
Then birth
Oogenesis - sexual maturity
- 1a oocyte complete division (meiosis I) –> 2a oocyte
- 2a oocyte divides (meiosis II, metaphase II)
- Fertilization is needed to complete meiosis II
