cell organelles Flashcards
cytoskeletal filaments
provide tracts for moving organelles around and for directing traffic of vesicles between them.
motor proteins
drive the skeletal filaments movements, that use energy of ATP hydrolysis to propel the organelles and vesicles along the filaments.
organelles examples:
cytosol
cytoplasm
nucleus
endoplasmic Reticulum
Golgi Apparatus
mitochondrion
lysosome
peroxisome
vacuole
cytosol =
concentrated aqueous gel
cytoplasm
cytosol + membrane bounded organelles except nucleus
Cytoskeleton
a network of protein filaments that extend throughout the cell: actin filaments, microtubules & intermediate filaments.
The cytoskeleton allows for the movement of organelles around the cell.
nuclear lamina
Array of protein filaments, anchor-sites for chromatin
nucleolus
Prominent structure in non-dividing nucleus
Nuclear Pore
Are protein-lined channels in the nuclear envelope.
Appear as perforations on the surface of the nucleus.
Allow for passage of materials from the nucleus to the cytoplasm.
what is the nucleolus site of???
it is the site of RNA transcription and processing and ribosome assembly
Chromatin
genomic DNA + proteins
nucleosome
is a structure where DNA is tightly packed around proteins known as histones
Heterochromatin
This is the condensed form of chromatin organisation and is the inactive form of chromatin.
Euchromatin
It is the lighter region of the nucleus and is most abundant in active cells because it is the active form of chromatin.
the nucleoplasm contains substances such as :
Nucleotides (for DNA replication and transcription)
Proteins/Enzymes (for all nuclear functions)
3 Key Processes of the Nucleus
Replication
Transcription
Translation
Replication
mediates copying of DNA in the cell cycle which is essential for the development and growth of a cell.
Transcription
controls the production of messenger RNA is produced in the nucleus using DNA as a template.
Translation
mRNA is transported via the nuclear pores to the cytoplasm for the synthesis of specific proteins which in turn have specific cellular functions (e.g. regulating metabolism, initiating mitosis)
LSU and SSU
are described as Svedberg (s) units
Svedberg (s) units
which are based upon their rate of sedimentation in a centrifuge.
SMOOTH ER
Agranular ER - has no ribosomes attached
ROUGH ER
Granular ER - has ribosomes attached
Functions of ER
The general function of the ER is in the synthesis, activation and transport of macromolecules in the cell, however depending on the addition of ribosomes or not, the ER has specific functions such as:
SMOOTH ER: outer surface lacks ribosome. Contains enzymes important in synthesis of lipids and steroids, detoxification of drugs and poisons, metabolism of carbohydrates, stores CA2+, enzyme reactions.
ROUGH ER: ribosomes stud outer surface, proteins produced on ribosomes, protein and lipid transport and secretion.
cisternae
network of membranous tubules and sacs
Golgi Apparatus
Distribution and shipping centre for the cells chemical processes
CIS FACE (near face)
receiving area
(convex)
TRANS FACE
shipping area
(concave)
Functions of the Golgi
products synthesised in the ER are transported to the GA for the following functions:
Modification of products (with Golgi enzymes)
Storage of products
Sorting and Transport of products for various parts of the cell
Lysosomes
membranous sac of hydrolytic enzymes, produced in the Golgi
Digestive Enzymes
break down cellular waste products, fats, carbohydrates and proteins which sent back to the cell to serve as building blocks for new products.
PHAGOCYTOSIS
cell engulfs microorganisms/large particles, fusion with lysosome. Digestion products, simple sugars, amino acids pass into cytosol.
AUTOPHAGY
recycling of cells own organic material, damaged organelle becomes surrounded by membrane, fusion with lysosome: cell continually renews itself.
Lysosomal enzyme Examples
LIPASE digests lipids
AMYLASE digests carbohydrates
PROTEASES digest proteins
NUCLEASES digest nucleic acids
PEROXISOMES
Specialised metabolic compartment bounded by single membrane.
first isolated from liver cells.
Contain enzymes that transfer hydrogen from various substrates to oxygen, producing hydrogen peroxide as a by-product.
oxidative reactions include:
Break down fatty acids into smaller molecules that can be transported to mitochondria.
Destroy toxic molecules
hydrogen peroxide itself is toxic: enzymes contained in peroxisome that converts it to water.
How To Identify Lysosomes & Peroxisomes
LYSOSOMES:
Larger
Darker in color
PEROXISOMES:
Smaller
Lighter in color
vacuole
is a membrane-bound sac
formed by pinching in of the plasma membrane
what is the endomembrane system?
A group of cell membranes and organelles that are mutually interconnected, either by being directly continuous with one another or by sending one another vesicles.
what organelles form the endomembrane system?
Nuclear envelope
Endoplasmic Reticulum
Golgi Apparatus
Lysosomes
Vacuoles
Plasma Membrane
Mitochondrial Membranes
Outer Membrane
Inter-membrane Space
Inner Membrane
Matrix
Outer Membrane
Contains integral proteins called porins (allow molecules to freely diffuse from one side of membrane to other)
Inter-membrane Space
Between outer and inner membrane. Outer membrane is freely permeable to small molecules so concentrations of ions and sugars in this space is same as cytosol.
Inner Membrane
Double phospholipid layer, site of ATP production. Cristae folds allow more surface area so that ability to produce ATP enhanced.
Matrix
Fluid that fills area inside inner membrane. Also important for ATP production with the aid of ATP synthase contained in inner membrane.
Mitochondrial DNA
mtDNA has a high mutation rate compared to nuclear DNA.
Used to study maternal family lines ad recent evolutionary events.
Photosynthesis
converting light energy to chemical energy and thus food for the plant.
stroma
contains the chloroplast DNA and ribosomes. Chloroplasts replicate autonomously.
Lamella
are internal membranes with stacks of hollow disks called thylakoids
Thylakoids
contains chlorophyll which absorbs the light and begins the process of photosynthesis.
