SI Week 3 Flashcards
nuclear envelope
double folded plasma membrane bound on inside of cell by the nuclear lamina
nuclear pores
8 large protein granules arranged in an
octagon, allowing a passageway for
materials to pass out of the nucleus
nucleus
where ribosomes and DNA are
ribosome synthesis takes place here
Chromatin
compact coils of DNA and associated proteins that wrap around histones, also many
regulatory proteins with functions in
controlling gene expression
Nuclear Lamina
network of protein fibers (intermediate filaments) that help maintain nuclear shape
Endoplasmic Reticulum structure
Folded into series tubules called cisternae
SER v RER
SER
- no ribosomes
-SER in liver cells is site of
synthesis + hydrolysis of
glycogen
- also site of drug detox and
phospholipid synthesis
- serve a Ca2+ reserve
RER
- ribosomes
- protein synthesis
- directs proteins to various
locations for maturation (Golgi),
secretion, etc.
Golgi Apparatus
cite of functional maturation of proteins and some polysaccharides
Steps of protein synthesis
- DNA to mRNA,
- mRNA exists through nuclear pores into cytoplasm
- ribosmes pick um mRNA and translate it into a polypeptide chain
- SRP bind to signal peptides
- SRP binds to the SRP receptor protein
- Polypeptide chain is injected into lumen as it is synthesized
- Enzymes in lumen cleave off the protein (Further modifications such as glycosylation may occur.) ribosome break apart and fall off
- Vesicle containing protein breaks off ER and merges with cis face of Golgi A. (Enzymes in cisternae modify protein as needed.)
- Vesicles break off at trans face of GA.
- Vesicle fuses with plasma membrane and expels contents into the extracellular fluid
Mitochondria Structure & Function
Structure:
- 2 membranes: inner/outer
- inner membrane folded into cristae
- inside cristae = matrix
- b/w membranes is inner molecular space
Function:
- inside matrix = enzymes important for cellular respiration
- produce ATP
Chloroplast Structure & Function
Structure:
- 2 membranes
- stroma (matrix) in aq. environment
- thylakoids stacked into structures called grana
Function:
- thylakoids are where chlorophyll are located
- photosynthesis in plant cells (energy)
3 Types Cytoskeleton
- Microfilaments
- intermediate filaments
- microtubules
Microfilaments Composition and Function
Composition:
- thinnest
- 2 intertwined strands of actin
Function:
- muscle contraction
- cell motility
- tension bearing (cell shape)
Intermediate Tubules
Composition:
- fibrous proteins (keratin) super coiled into cables
- midsized
Function:
formation of nuclear lamina (keep nucleus from collapsing onto DNA)
- anchorage of nucleus
Microtubules
Composition
- Tubulin dimer ( alpha and beta tubulin)
- hollow
Function
- cell motility
- organelle movement
- chromosome movements in
