Eukaryotic Cell Organelles + Cytoskeleton

Mitochondria

Where majority of the cells’ ATP is made.

Outer (permeable) membrane separates mitochondria from cytoplasm

Inner (non-permeable) membrane is where ETC occurs

Contains phospholipids + proteins + DNA

Mitochondrial Matrix

Is the innermost area

Contains 70s ribosomes, circular maternal DNA, RNA, protein, coenzymes NADH, FADH2, carbon molecules

Is where DNA replication, transcription, translation, pyruvate decarboxylation, Krebs cycle, ETC

Rough Endoplasmic Reticulum

Contains phospholipids, ribosomes, proteins, RNA (m,t,r), carbohydrates

Roles: synthesis of secretory pathway proteins, post translational modification e.g. formation of disulphide bridges, protein folding etc.

Smooth Endoplasmic Reticulum

Contains phospholipids, other lipids, carbohydrates, Ca2+

Roles: lipid synthesis, carb metabolism, detox via cytochrome P450 enzyme systems, Ca2+ storage

Golgi Apparatus

Contains phospholipids, proteins, carbs, lipids

Role: modifies ER proteins, sorts and sends proteins

Vesicles

membrane spheres that carry cargo, content can include anything that can be found inside ER/Golgi, they are made of phospholipids

RIBOSOMES NOT ORGANELLES

Contains protein, rRNA, made up of a large and small subunit, their role is translation of mRNA into protein

Lysosomes

Organelles that fuse with vesicles and deposit lyric enzymes inside

Contains phospholipids, lyric enzymes

Interior is very acidic, lyric enzymes need low pH

Lysosomes can fuse with…

Endosomes: vesicles formed by endocytosis

Phagosomes: vesicles formed by phagocytosis

Autophagosomes: vesicles formed by autophagy

Role: digestive function

Peroxisomes (Microbody)

Contain oxidases, catalases + phospholipids

Break down of long chain fatty acids through beta oxidation.

Detoxification of H2O2, byproduct of cellular processes by catalase.

Involved in lipid metabolism and synthesis of bile acids in liver cells.

Located in cytoplasm of almost all eukaryotic cells, in humans are especially concentrated in kidney and liver cells.

Formed via E.R or other peroxisomes

Oxidases oxidise toxic materials and fatty acids producing H2O2

in liver cells+ kidney cells peroxisomes detoxify alcohol and other harmful substances

2H2O2 → 2H2O + O2

Cytoskeleton

Contains 3 filaments

1. Microtubules

2. Intermediate filaments

3. Microfilaments (actin filaments)

Microtubules

Hollow tubes made from alpha and beta tubulin (protein) dimers.

They are dynamic, can be lengthened or shortened at their two ends, called plus and minus end. Technically tubulin can be added or removed at either end, but the plus end is where more tubulin is added, and minus end is where tubulin is removed.

Make up:

mitosis spindle, cilia, flagella, centrioles, basal bodies, transport vesicles + organelles, Microtubule Organizing Centre (MTOC), mitotic spindle

Intermediate Filaments

Made from various protein monomers (e.g. Vimentin) forming 2 filaments that arrange in double helix.

Make up nuclear lamina

Are not dynamic

Microfilaments/Actin filaments

Made from actin monomers forming 2 filaments that arrange in a double helix

Gross movement of cell e.g. formation of pseudopods

Maintaining/changing shape of cell

Are dynamic, have a + and - end

Chloroplasts

Organelles found in plant cells and some protists.

Has 3 membranes; outer, inner, and thylakoid

The inner + outer membranes contain phospholipids and proteins

Thylakoid membrane contains phospholipids, proteins, chlorophyll, light rxn (photosynthesis) occurs here

Found in leaves and other green parts of plants

Cell Wall

helps plant resist osmotic pressure

Stroma (in Chloroplasts)

Contains 70s ribosomes, circular DNA, RNA, protein, carbohydrates, NADPH (coenzyme)

Roles: DNA replication, transcription, translation, Calvin cycle (photosynthesis)

Plasmodesmata

Channels connecting plant cells allowing cytoskeleton to flow between separate cells, allows for transport and communication between plant cells

Central Vacuole

Stores water inside the cell, and maintain pressure and thus the shape of the plant

Plastids

Membrane bound organelles, primarily found in plants and algae, not in fungi.

Types: chloroplasts, chromoplasts, leucoplasts (amyloplasts, elaioplasts, proteinoplasts)

Chromoplasts

involved in pigment synthesis + storage, contain pigments other than chlorophyll e.g. carotenoids (give carrots orange colour) and xanthophylls. Also responsible for colours in fruits, flowers, autumn leaves.

Leucoplasts

Colourless plastids that are primarily involved in synthesis and storage of starch, oils and proteins. Found in parts of the plant that need no light e.g. roots and seeds. Can differentiate into amyloplasts (starch storage), elaioplasts(oil storage), proteinoplasts(protein storage).

Membrane Structure of Plastids

Surrounded by a double membrane envelope and contain their own DNA, which is circular similar to bacteria. Supports endosymbiosis, suggests that plastids originated from ancient free-living prokaryotes that were engulfed by ancestor eukaryotic cell.

Division

Can divide and replicate independently of cell division cycle, can also be differentiated from one type to another depending on cell’s needs.