Chapter 4: Evolutionary origin of cells and their general features Flashcards
stage 1 of the origin of living cells on Earth
nucleotides and amino acids were produced prior to the existence of cells
prebiotic soup
accumulation of organic molecules and macromolecules in a vastly different Earth
reducing atmosphere hypothesis
earth rich in water vapor, ammonia, hydrogen gas, methane, and a lack of oxygen gas
extraterrestrial hypothesis
carbon-based organic molecules brought by carbonaceous chondrites
deep-sea vent hypothesis
conversion of N2 to ammonia near deep-sea vents
stage 2 of the origin of living cells on Earth
polymerization of nucleotides to form RNA and DNA, and amino acids to proteins
stage 3 of the origin of living cells on Earth
polymers became enclosed in membranes
protobiont
organic molecules/macromolecules that acquired a boundary
stage 4 of the origin of living cells on Earth
RNA world
hypothetical period when RNA stored information, self-replicated, and catalyzed reactions (ribozymes)
chemical selection
chemical evolution
light microscope
uses light for illumination
electron microscope
uses a beam of electrons for illumination
2nm resolution limit
transmission electron microscopy (TEM)
a beam of electrons is transmitted through the biological sample
sample is stained with a heavy metal
*not used to view living cells
scanning electron microscopy (SEM)
used to view the surface of a biological sample
sample is coated with a thin metal
*not used to view living cells
resolution
the ability to view two adjacent objects as distinct from each other
contrast
the ability to visualize a particular cell structure based on how it looks from adjacent structures
magnification
the ratio between the size of an image produced by a microscope and the object’s actual size
genome
the entire compliment of its genetic material
genes
contain information to produce cellular proteins with specific structures and functions
prokaryotes
bacteria and archaea
components of prokaryotes
plasma membrane cytoplasm nucleoid ribosomes cell wall glycolax pili flagella (provide motility)
eukaryotes
animals, plants, fungi, and protists
organelle
compartmentalization
liquid-liquid phase separation
aggregate solutes separate from the bulk solvent to form a dropplet
differential gene regulation
every cell expresses a unique set of mRNAs
proteome
the complete set of proteins that a cell is currently making
cytosol
the region outside the membrane-bound organelles and inside the plasma membrane
metabolism
sum of chemical reactions by a cell or organism
enzyme
a protein that accelerates the rate of a chemical reaction
catabolism
breakdown of a molecule into a smaller one
anabolism
synthesis of molecules into macromolecules
cytoskeleton
network of cellular fillaments
microtubules
intermediate filaments
actin filaments
microtubules
25nm diameter
hollow
α- and β-tubulin
grow only on the + side - attached to centrosome
cell shape organization of organelles chromosome sorting intracellular movement of cargo cell motility
dynamic stability
oscilation between growing and shortening faces in microtubules
centrosome
microtubule-organizing center
intermediate filaments
10nm diameter
twisted
keratin, lamin
cell shape
mechanical strenght
anchorage of cell and nuclear membrane
actin filaments
7nm
spiral
actin
cell shape
cell strenght
intracellular movement of cargo
cell division in animals
motor proteins
use ATP to produce various types of movement
head (catalyc site)
hinge (place of movement)
tail (achor)
movement of cargo
motor proteins move
kinesin
movement of filament
motor proteins are fixed in place
myosin
bending of a filament
motor proteins and filaments are fixed in place
dynein
flagella/cilia
appendages that provide motility
dynein
axoneme
basal bodies
endomembrane system
network of membranes
nuclear envelope endoplasmic reticulum Golgi apparatus lysosomes vacuoles peroxisomes
nuclear envelope
double-membrane structure
nuclear pores
chromatin
complex formed between DNA (chromosomes) and proteins such as histone
nuclear matrix
nuclear lamina: intermediate filaments and internal nuclear matrix
nucleolus
assembly of ribosomal subunits
*proteins in ribosomes are made in cytoplasm but assembled in the nucleolus
endoplasmic reticulum (ER)
network of membranes that form cisternae
lumen (space inside cisternae)
rough ER
studded with ribosomes
protein sorting
insertion of membrane proteins
glycosalation (attachment of carbs. to proteins and lipids
smooth ER
metabolism
storage of Ca 2+
lipid synthesis and modification
Golgi
cis (close to ER)
medial
trans (close to plasma membrane)
*protein sorting
*processing
glycosalation
proteolysis (enzymes proteases cut polypeptides)
*secretion
lysosome
small organelles that break down molecules and macromolecules
acid hydrolases
vacuoles
site that provides storage and/or cell shape regulation
central vacuole
80% or more of cell’s volume
storage
space-filling
Turgor pressure
contractile vacuole
expands as water enters the cell and merges with plasma membrane to release excess water
food vacuole
degradation of food
peroxisomes
organelle where toxins are broken down
catalase (enzyme)
sorting signals
short stretches of amino acid sequences within proteins that direct them to their correct cellular location
cytosolic proteins
complete their synthesis in the cytosol and remain there due to lack of signaling
contranslational sorting
proteins with an ER sorting signal, destined for the ER, Golgi, lysosomes, or plasma membrane
post-translational sorting
completely synthesized in the cytosol and contain sorting signals that destin them to the nucleus, mitochondria, chloroplast of peroxisome
extra-cellular matrix
strenght:
structural support
organization
cell signaling
glycosaminoglycans
proteoglycans
chitin (in invertebrates)
