Cell Structure

What are the components of the Nucleus

• Nuclear envelope

• Nuclear pores

• Nucleolus

What is the structure of the Nuclear Envelope

• what are the membranes made of

• A double membrane structure that has a number of pores

• Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers

What is the function of the Nuclear Envelope

The pores in the nuclear envelope control the passage of ions, molecules and RNA between the nucleoplasm and cytoplasm

What is the structure of the Nucleus

• what does it contain

• The nucleoplasm is the semi-solid fluid inside the nucleus, where we find the chromatin and the nucleolus

• Contains linear chromosomes that are made up of DNA

What is the structure of the Nucleolus

• what proteins is it made up of

• The nucleolus is the largest sub-structure within the nucleus

• The nucleolus is made of proteins, RNA and DNA

What is the function of the Nucleolus

• what is its secondary role

• The main role of the nucleolus is to act as the site at which ribosomes are made

• The nucleolus also has secondary roles, such as immobilising proteins and forming signal recognition particles

What is the structure of the Mitochondria

• What does the mitochondrial matrix contain

• What is the membrane made of

• Oval-shaped, double-membrane organelles that have their own ribosomes and DNA

• Each membrane is a phospholipid bilayer embedded with proteins

• The inner layer of the membrane has folds called cristae

• The area surrounded by the folds is called the mitochondrial matrix

• The mitochondrial matrix contains enzymes used for respiration

What is the function of the Mitochondria

• why do muscle cells have a high concentration of mitochondria

• Mitochondria make ATP via aerobic respiraton

• Muscle cells have a very high concentration of mitochondria because they are highly active and need a lot of energy to keep the body moving

What is the structure of Chloroplasts

• Chloroplasts have their own DNA, ribosomes and have inner and outer membranes

• The space enclosed by the inner membrane contains a set of interconnected and stacked fluid-filled membrane sacs called thylakoids

What are some features of Thykaloids

• Each stack of thylakoids is called a granum (plural = grana)

• Grana are linked by lamellaeLamellae are flat, thin parts of thylakoid membrane

• The fluid enclosed by the inner membrane that surrounds the grana is called the stroma

What is the function of the Chloroplasts

• Photosynthesis is the series of reactions that use carbon dioxide, water and light energy to make glucose and oxygen

• This process happens in chloroplasts and allows plants to make their own food (e.g. sugars)

What is the structure of the Golgi Apparatus

• what are the two sections divided in to

• The Golgi apparatus is a series of flattened membranous sacs

• Divided into two sections cis and trans networks

What is the function of the Golgi apparatus

Stores and modifies proteins and triglyceridesIt then packages these substances into vesicles for transportation

What is the structure of Golgi vesicles

• Golgi vesicles are membrane-bound, fluid-filled vesicles located in the cytoplasm

• They are small, round and are seen in a high density near the edges of the Golgi sacs.

• Lysosomes are a type of Golgi vesicle

What is the function of Golgi vesicles

Golgi vesicles store and transport modified proteins and lipids from the Golgi apparatus to target cells

How do Lysosomes work

• what do they break down

• Lysosomes are a special type of Golgi vesicle

• They contain enzymes called lysozymes

• Lysozymes aid the breakdown of proteins, polysaccharides, lipids, nucleic acids and old organelles

What is the function of ribosomes

Ribosomes are in charge of protein synthesis.

Protein synthesis is an essential function of all cells.

What is the structure of ribosomes

• are they membrane bound

• what are they made of/are they covered by a membrane

• Ribosomes can be free floating in the cytoplasm or attached to the cytoplasmic side of the endoplasmic reticulum (ER)

• Ribosomes are very small organelles made of protein subunits

  • This means that ribosomes are not covered by a membrane

What is the structure of the ER

• including sER and rER

• what is the membrane made of

The ER is a series of interconnected folded membranous sacs and tubules.

• The membrane of the ER is a phospholipid bilayer embedded with proteins

• The smooth ER (sER) membrane has no ribosomes

• the rough ER (rER) membrane has many ribosomes on its surface

What is the function of the rER

The RER is responsible for processing and folding proteins and glycoproteins and transporting them to vesicles

What is the function of the sER

The SER is responsible for making and processing lipids and carbohydrates and transporting them to vesicles

What are features of phospholipids

• what are they the primary component of

• they are the primary component of the plasma membrane

• they are amphipathic

• contain hydrophobic and hydrophilic regions

What are features of having hydrophobic and hydrophilic regions in a plasma membrane (inside phospholipids)

The hydrophilic region faces outwards and the hydrophobic region inwards

This means that polar substances can't easily pass through the membrane

What is the function of the plasma membrane

• Plasma membranes protect cells from their surrounding environment

• The partially-permeable nature of plasma membranes means that they can selectively allow certain molecules to pass through and stop othersIn this way, these membranes mediate the interactions between a cell's interior and its surroundings

What is the structure of cell walls in fungi and plants

• The major organic molecule in fungal cell walls is chitin

• Plant and algal cell walls are made of cellulose

• Cellulose is a polysaccharide made up of glucose units

What is the function of cell walls

to provide structural support and rigidity

What is the structure of centrioles

• how are they found

• Centrioles have a cylindrical shape

• They are made up of parallel microtubules that surround a central cavity

• Found as pairs arranged at 90 degrees

• Centrioles are only found in isolation when in the basal regions of flagella and cilia

What is the function of centrioles

• what does it organise

• Organise the microtubules for cell division

• Centrioles help to organise the mitotic spindle during cell division

What is the structure of flagella

• what is the arrangement of eukaryotic cells

• what is the flagella made of in prokaryotes (protein name)

• Eukaryotic flagella are described as having a nine-plus-two arrangement of microtubules

• Bacteria flagella are helical and are mainly made up of the protein flagellin

What is the structure of cilia

• primary and motile arrangement

• what is the central core called

• Like flagella, cilia have a central core called the axoneme

• Primary cilia have a nine-plus-zero arrangement

• Motile cilia have a nine-plus-two arrangement

What is the function of the cilia

• Cilia generate the locomotion of the phylum Ciliophora

• Cilia can also help to move substances internally in organisms by synchronising their beating

What are the functions of the cytoskeleton

• what does it maintainin terms of cell movement

• Maintaining the shape of the cell

• Securing some organelles in specific positions

• Allowing cytoplasm and vesicles to move within the cell

• Enabling cells within multicellular organisms to move

What are the types of fibres within the cytoskeleton and their function

Microfilaments

• thicken the cortex around the inner edge of a cell

• they resist tension

Intermediate filaments

• found throughout the cell and hold organelles in place

Microtubules

• found in the interior of the cell where they maintain cell shape by resisting compressive forces

• main role is during mitosis

What is the structure of microfilaments

• what protein is it made from

• Microfilaments bear the tension of the cell

• Microfilaments are the narrowest protein fibres in the cytoskeleton

• They are made of two intertwined strands of a globular protein called actin

What is the function of microfilaments

• why are they important in cellular events requiring motion

• Microfilaments also provide rigidity and shape to the cell

• They can disassemble and reform quickly, allowing the cell to change its shape and move

• Actin works together with a motor protein, called myosin

• So, microfilaments are important for cellular events requiring motion (like eukaryotic cell division)

What is the structure of Intermediate Filaments

Intermediate filaments are made of several strands of fibrous proteins that are wound together

What is the function of intermediate filaments

They bear tension, maintaining the shape of the cell, and anchor the nucleus and other organelles in place

What is the structure of microtubules

• what proteins are they made from (polymerised dimers)

• Microtubules are the widest components of the cytoskeleton

• They are small hollow tubes, with walls made from polymerised dimers of two globular proteins (α-tubulin and β-tubulin)

• Microtubules are the structural elements of flagella, cilia and centrioles

• Microtubules can disassemble and reform quickly

What is the function of Microtubules

• what do they help

• what do they provide for vesicles in cell division

• what do they pull

• Help the cell resist compression

• Provide a track along which vesicles move through the cell

• Pull replicated chromosomes to opposite ends of a dividing cell

Define resolution

Resolution is the ability of a microscope to distinguish two adjacent structures as separate

Outline the features of a light microscope

• how it worksdetails about the specimen and staining

• Visible light passes and is bent through the lens system to enable the user to see the specimen

• The specimen can be aliveIndividual cells are generally transparent and their components are not distinguishable unless they are coloured with special stains

• Staining usually kills the cells.

Why is there a higher magnification and resolution in electron microscopes

• electron microscopes use a beam of electrons instead of a beam of light

• This allows higher magnification and higher resolving power

• This means that more detail can be seen.

Outline the features of a TEM microscope and how it works

• In a TEM, the electron beam penetrates the cell and provides details of a cell’s internal structures

• TEMs use electromagnets to focus the electron beam

• TEMs are high resolution microscopesIn thin specimens, you can see the internal structures of organelles such as chloroplasts.

What organelles are involved in cell division

• Microtubules

• Microfilaments

• Centrioles (organise microtubules)

Plant cell walls are made of cellulose, what is it comprised of?

It is a polysaccharide of glucose units

How does the structure of the rough endoplasmic reticulum help enable the synthesis of proteins?

The rough endoplasmic reticulum has ribosomes and a large surface area

In prokaryotic cells, the cell wall is made of

peptidoglycan

If the Golgi app has been altered in any way, how might this affect protein production

If proteins undergo further processing in the GA, and it's altered or deformed, the modifications that would normally take place may lead the protein to not function correctly or at all

Suggest how abnormalities in the cytoskeleton may lead to may affect protein production

• If the cytoskeleton is disrupted, proteins may not be transported between the RER and the Golgi body, which will prevent them from being modified

• They also may not be transported between the Golgi body and the cell surface, preventing them from being secreted