Chapter 1 Flashcards
The human body is composed of how many cells?
between 10^12 – 10^16
(trillions)
Mention differences between prokaryotic vs eukaryotic cells
Prok: <5 microm, Euk: >10microm
Prok: always unicellular
Euk: often multicell
Prok: no nucleus or membrane-bound organelles
Euk: nucleus and membrane-bound organelles
Prok: DNA circular without proteins
Euk: DNA linear and associated with proteins
Prok: 70S, euk: 80S
PRok: no cytoskeleton, euk: always
Prok: flagellin, euk: tubullin
Arguments for endosymbiosis?
- own DNA
-produce many proteins and
enzymes - own double membrane
- reproduce like bacteria
Cytoplasm vs cytosol?
Cytoplasm: Contents of the cell that are contained within its plasma
membrane, excluding the nucleus.
Cytosol: part of the cytoplasm that is not held by any of the organelles in the
cell.
Cytosol: homogenous mixture of..
Water (main component)
* Structural material
* Enzymes
* Macromolecules
* Metabolites
* Coenzymes
* Free nucleotides
* Metabolic effectors
* Inorganic ions and others
They represent half of the
overall cellular volume.
Organelles
The majority of the metabolism in eukaryotic and prokaryotic
cells occurs in…
Aqueous departments:
Cytosol (prokaryotic and eukaryotic cells).
* Nucleoplasm (eukaryotic cells).
* Interiors of cytoplasmic membrane-bound organelles
(eukaryotic cells).
What organelles are there in a typical eukaryotic cell?
Nucleus
Endoplasmic Reticulum
Golgi apparatus
Endosome
Lysosome
Mitochondria
Peroxisome
Function ER~?
- helps process molecules created by the cell.
- transports these molecules to their
specific destinations (in- or outside)
Golgi apparatus: function?
packages molecules processed by the endoplasmic reticulum to be transported out of the cell.
Lysosomes and peroxisomes: function?
- digest foreign bacteria
- rid toxic substances
- recycle worn-out cell components.
Ribosomes: where?
float freely or connected to ER
Cytoskeleton (not an organelle): function?
- Determines cell shape,
- Participates in cell division,
- Allows cells to move.
- Provides a track-like system that directs the
movement of organelles and other substances
within cells.
Cell-environment relationship is essential for..
Cell proliferation, differentation, interactions, movement
In In cartilage and bone, fibroblasts are called
chondroblasts and osteoblasts respectively.
Cell that produces components or EM locally:
fibroblasts
Extracellular matrix (EM) is…
intricate network of fibrous proteins (collagen, elastin etc) and
polysaccharides that surround, support, and give structure to cells and
tissues in the body.
Where can we find the EM?
- Basement membrane (basal lamina)
- Epithelia, endothelia, muscle, fat, nerves
- Elastic fibers
- Skin, lung, large blood vessels
- Stromal or interstitial matrix
- Bone, tooth, and cartilage
- Tendon and ligament
Functions of the EM?
- structural support, maintain cell organization
- Compartmentalize tissues
- Provide hardness to bone and teeth
- Present information to adjacent cells:
- Facilitate cell migration during:
– Development
– Normal tissue maintenance
– Injury
– Disease
What are the four functional groups of types of Junctions?
- ANCHOR JOINTS
- occlusive joints
- CHANNELFORMING JOINTS
- signal transmitting joints
Anchoring joints:
cell-cell or cell-matrix?
function?
both cell-cell and cell-matrix adhesions
- transmit stresses
- tethered to cytoskeletal filaments
Occluding junctions:
cell-cell or cell-matrix?
function?
Cell-cell
Seal gaps between cells: impermeable (or selective) barrier
Channel-forming junctions
Create passageways (cell-cell?)
Signal-relaying junctions
Allow signals to go from cell to cell
Four forms of intercellular signaling:
- Contact-depending signal
- Paracrine/autocrine
- Synaptic
- Endocrine
Contact-dependent signaling: requires.. when is it important?
- Requires cells to be in direct membrane-membrane contact.
- It is especially important during development and in immune responses
What allows neighbouring cells to signal?
GAP JUNCTIONS
Paracrine signaling: what is it? What other form?
local mediators released into the extracellular
space and act on neighboring cells.
Other form: autocrine (cancer cells)
Synaptic signaling: what is it?
neurons: releasing neurons at synapses through electric signalling
Endocrine signalling: what is it?
Endocrine cells secrete hormones into the bloodstream, carried far & wide
