MCBG Session 1 - Introduction to Cell and its Components Flashcards
Jog your memory with the structure and function of the following:
- Nucleus
- Nucleolus
- Nuclear membrane
- Microtubules
- Centrioled
- Microvillii
- Microfilament
- Mitochondrion
- Cytoplasm
- rER
- Ribosome
- Cell membrane
- Peroxisome
- sER
- Released secretions
- Secretory vesicle
- Golgi complex
- Lysosome
- Nucleus – the cell’s control centre, containing chromatin and most of the cell’s DNA.
- Nucleolus – the region at the centre of the nucleus; plays a vital role in ribosome production.
- Nuclear membrane – a two-layered selectively-permeable membrane with pores for substances to enter and leave the nucleus.
- Nucleoplasm – fluid within the nucleus in which the nucleolus and chromatin float.
- Microtubules – part of the cell’s cytoskeleton, these aid movement of substances through watery cytoplasm.
- Centriole – Composed of two cylinders of tubules; essential to cell reproduction.
- Microvilli – these projections increase the cell’s surface area, aiding absorption of nutrients.
- Vacuole – sac that stores and transport ingested materials, waste products and water.
- Cytoskeleton – internal framework of the cell, made up of microfilaments and hollow microtubules.
- Microfilament – provides support for the cell; sometimes linked to cell’s outer membrane.
- Mitochondrion – site of fat and sugar digestion in the cell (cellular respiration), produces energy.
- Cytoplasm – jelly-like fluid in which organelles float; primarily water, but also contains enzymes and amino acids.
- rER – consists of folded membranes, studded with ribosomes, that extend throughout the cell; helps transport of materials through the cell; site of much protein manufacture.
- Ribosome – tiny structure that assists with protein assembly.
- Cell membrane – encloses contents of the cell and maintains the cell’s shape; regulates flow of substances in and out of the cell.
- Peroxisome – makes enzymes that oxidise some toxic chemicals
- sER – network of tubes and flat curved sacs that helps to transport materials through the cell; site of Ca storage; main location of fat metabolism
- Released secretions – secretions are released by exocytosis, when a vesicle merges with the cell membrane and releases its contents.
- Secretory vesicle – sac containing various substances, such as enzymes, that are produced by the cell and secrete at the cell membrane
- Golgi complex – a structure that processes and repackages proteins produced in the rER for release at the cell membrane
- Lysosome – produces powerful enzymes that aid in digestion and excretion of substances and worn-out organelles
What are the two types of chromatin?
- Chromatin is found in two varieties: euchromatin and heterochromatin.
- Originally, the two forms were distinguished cytologically by how intensely they stained – the euchromatin is less intense, while heterochromatin stains intensely, indicating tighter packing.
What is limit of resolution?
Limit of resolution - the minimum distance at which two objects can be distinguished.
Outline the structure and components of prokaryotic cells.
- Prokaryotic cells have an external membrane but no internal membranes. All the biochemical processes of the cell occur in the same compartment.
- Components:
I. Capsule
II. Cell wall
III. Plasma membrane
IV. Flagella
V. 70s Ribosomes
VI. Cytosol
VII. Nucleoid
VIII. Pili
Outline the structure and components of a eukaryotic cell.
- Eukaryotic cells, by contrast, are compartmentalised by internal membranes.
- Components:
I. Plasma membrane
II. Vacuole
III. Nuclear envelope
IV. Nucleolus
V. Chromosome
VI. Lysosome
VII. Basal bodies
VIII. rER and sER
IX. Golgi Complex
X. Cytosol
XI. Free ribosomes
XII. Mitochondria
Describe the structure of plasma membranes.
- Plasma membranes are composed of a phospholipid bilayer.
- They are ampipathic.
- The phospholipid bilayer (membrane) forms a relatively impermeable barrier to most water-soluble molecules.
- Membrane proteins can be associated with the lipid bilayer in different ways. They can be transmembrane (integral) or peripheral proteins.
Describe the functions of the plasma membrane.
- Selective permeability
- Transport of materials along cell surface
- Endocytosis
- Exocytosis
- Intercellular adhesion
- Intercellular recognition
- Signal transduction
What is glycocalyx?
The cell coat (glycocalyx) is made up of oligosaccharide and polysaccharide side chains on the outside of the plasma membrane.
Outline the Fluid Mosaic Model.
- Hydrophobic fatty acid tails in the middle and the hydrophilic heads on the outside.
- Part of the plasma membrane would be the integral proteins, peripheral proteins, transmembrane proteins, Phospholipids form a bi-layer.
- Have the hydrophobic tails which are attracted to each other, with the hydrophilic heads on either end interacting with the cytoplasm and extracellular environment.
- A bilayer is formed as the two hydrophobic tails create an impenetrable barrier to hydrophilic molecules which must use a channel to get in and out of the cell.
Describe the structure of the smooth and rough ER.
- The smooth endoplasmic reticulum (sER) is found in the liver, mammary gland (lipid biosynthesis) and in the ovaries, testes and adrenal gland (steroidogenesis).
- It is thought that the endoplasmic reticulum membrane is continuous and encloses a single lumen.
Distinguish between free and bound polyribosomes.
- Free polyribosomes, are found in the cytoplasm and synthesis proteins which remain in the cytoplasm
- Bound polyribosomes show protein synthesis and segregation into the rough ER.
Outline the structure and function of the Golgi apparatus.
The Golgi apparatus/body/complex functions to modify, sort, concentrate and package proteins synthesised on the rough endoplasmic reticulum.
Outline the structure and function of lysosomes.
Lysosomes are generated by the Golgi apparatus and contain many hydrolytic enzymes. Lysosomes fuse with material requiring digestion.
Distinguish between primary and secondary lysosomes.
- Primary lysosomes are formed from the Golgi apparatus while the secondary lysosome is formed by the fusion of the primary lysosome and an endocytotic/phagocytotic vesicle.
- The primary lysosome does not release its contents out of the cell but the secondary lysosome may release useful products (which will serve as building blocks of new materials) into the cytoplasm of the cell via facilitated diffusion, or release waste products or products that cannot be digested out of the cell via exocytosis.
Outline the structure and functions of mitochondria.
- Primary function – generation of potential energy (ATP) by oxidative phosphorylation.
- Double membrane – inner membrane thrown into folds (cristae).
- Can divide (own genetic information).
- DNA, ribosomes and division similar to bacteria (hence endosymbiosis theory).
- Female lineage.
What are microtubules?
Microtubules are long hollow cylinders made of the protein tubulin. It is found at sites where structures are moved (i.e. nerve fibres, the mitotic spindle, cilia and flagella).
