The Cell Flashcards
Totipotent
ability to differentiate into any cell in the body, eg. zygote
Nuclear envelope
double membrane, pores, continuous with RER
Nucleolus
spherical, dark body
Chromatin
compacted DNA wrapped around proteins, packs into chromosomes
Euchromatin
lightly stained, ACTIVE
Heterochromatin
intensely stained, INACTIVE
Process of transcription
DNA uncoils, sequence exposed, mRNA assembled by enzymes, sequence complementary to DNA, mRNA strand moves into cytoplasm through nuclear pore
Process of translation
mRNA binds to ribosomal unit and is decoded, tRNA aligns amino acids to make polypeptide chain
Cytosol
intracellular fluid, 75-90% water, 10-25% ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, waste products
Ribosome
2 subunits (small and large), site of protein synthesis, high RNA content, free and attached to ER
Smooth endoplasmic reticulum
synthesis lipids (fatty acids and steroids)
Golgi body (structure)
3-20 cisternae (small, flattened membranous sacs), entry (cis cisternae), exit (trans cisternae)
Vesicles
membrane bound, carriers
Mitochondria
double membrane, site of most ATP production, contains own DNA, can self-replicate
Lysosomes
contains enzymes that work best at pH<5
Microvilli
increase surface area, eg. digestive tract
Cilia
move fluid-like along cell surface, eg. respiratory tract
Flagella
move entire cell, eg. sperm
Anchoring proteins
attach plasma membrane to other structures
Recognition proteins
detected by cells of the immune system
Receptor proteins
bind to specific extracellular molecules called ligands (eg. ion or hormone)
Carrier protein
binds solutes and transports across plasma membrane
Protein channels
integral proteins containing a central pore forming a passageway across membrane
Diffusion (what substances)
fat soluble
Facilitated diffusion
via protein carrier (eg. pump or channel)
Osmosis
water
Three stages of cellular communication
- reception
- transduction (relay molecules in signal pathway)
- response (activation of cellular response)
Stages of mitosis
interphase, prophase, metaphase, anaphase, telophase
Interphase (including G0, G1, S, G2)
preparation for division
G0 (G naught) - normal cell function
G1 - cell function, generation of organelles
S phase - duplication of chromosomes, DNA replication, synthesis of histones and nuclear proteins
G2 - protein synthesis, centriole replication
Prophase
early - DNA uncoils/chromatin condenses
- nuclear membrane disappears
late - centrosomes migrate to poles
Metaphase
chromosomes align along metaphase plate, attached to microtubules held by centrioles
Anaphase
microtubules pull chromatids away from centre
Telophase
nuclear envelope reforms, DNA uncoils
Cytokinesis
cytoplasmic division of daughter cells
Cyclins
family of proteins involved in regulation of cell cycle
Apoptosis (what and why)
programmed cell death, intracellular processes (internal DNA damage, death receptor), cleared by macrophages, phagocytosis
Necrosis (what)
unplanned cell death, external stressors, blebbing (cell membrane fragments, swelling, nuclear fragmentation, cell rupture)
4 types of necrosis
- coagulative - protein denatured but shape maintained
- liquefactive - rapid lysis of cells by lysosomal degradation enzymes
- caseous - coagulative + liquefactive
- gangrenous - caused by ischemia (no blood supply) to large amount of tissue
