organelles

Question 1

what are organelles and why are they important for cells?

Answer 1

Organelles are specialized structures within cells that perform specific functions, similar to how organs work in the body. They are crucial for maintaining cell function and overall health, as they are responsible for various vital processes like energy production, protein synthesis, and waste removal.

Question 2

summary of ribosomes

Answer 2

**found in **
* prokaryotes
* eurkaryotes
function/feature
* found in all cells
* the site of protein synthesis, using the genetic code from the nucleus

Question 3

summary of the nucleus

Answer 3

**found in **
* eurkaryotes
function/feature
* enclosed within double membrane (nuclear envelope)
* contains the cell’s DNA
* controls DNA replication during cell division
* repairs genetic material
* initiates gene expression
* controls metabolic activites of a cell
* contains nucleolus

Question 4

summary of mitochondria

Answer 4

found in
* eurkaryotes
function/features
* main site of ATP production for energy (through cellular respiration)

Question 5

summary of endoplasmic reticulum

Answer 5

found in
* eurkaryotes
function/feature
* transport system within cells
* protein modification (rough er)
* lipid synthesis and storage, and detoxification (smooth er)

Question 6

summary of golgi apparatus

Answer 6

found in
* eurkaryotes
function/feature
* process, sort and package of proteins and lipids

Question 7

summary of lysosomes

Answer 7

found in
* eurkaryotes
funtion/features
* vesicle filled with digestive enzymes
* breakdown of non-functioning cell organelles and substances

Question 8

summary of peroxisome

Answer 8

found in
* eurkaryotes
function/features
* breakdown of substances toxic to the cell

Question 9

summary of cytoskeleton

Answer 9

found in
* eurkaryotes
function/features
* support and strength for the cell

Question 9

summary of centriole

Answer 9

found in
* eukaryotes - animals
function/features
* part of cytoskeleton
* role in cell division

Question 9

summary of chloroplasts

Answer 9

found in
* eukaryotes - photosynthetic species (such as plants)
function/features
* convert energy from the sun using photosynthesis

Question 10

summary of vacuole

Answer 10

**found in **
* eukaryotes - plants
function/features
* storage of nutrients and mineral salts
* waste disposal
* large and central in plant cells

Question 11

summary of cell wall

Answer 11

**found in **
* most prokaryotes, eukaryotes - plants, algae and fungi
function/features
* provides protection, shape and support to the cell.

Question 12

ribosomes

Answer 12

**ribosomes **are made of ribosomal RNA (rRNA) and proteins. these form 2 sub-units that lock together.
* Their function is protein synthesis, converting the genetic code (mRNA) into a chain of amino acids.
* ribosomes are small, but are numerous in the cell, they are found free floating in the cytoplasm or, in eurkaryotes, or attached to the rough ER

Question 13

what is the importance of proteins

Answer 13

Proteins are essential for building and repairing body tissues, supporting the immune system, and driving various metabolic reactions. (they are the building blocks for life)

Question 14

nucleus: the control centre

Answer 14

The nucleus controls cell functions in animals, plants, and fungi. It is a key part of eukaryotic cells, enclosed by a double membrane with pores that allow the exchange of large molecules like RNA and proteins. The nucleus is a membrane-bound organelle (double membrane) in eukaryotes that contains the cell’s DNA. Its functions include controlling DNA replication, repairing genetic material, initiating gene expression, and controlling metabolic activities.

Question 15

Nuclear Envelope & Pores, Describe the nuclear envelope and nuclear pore complexes.

Answer 15

The nuclear envelope is the double membrane surrounding the nucleus, perforated by nuclear pore complexes (NPCs), which are protein-lined channels controlling the exchange of materials between the nucleus and cytoplasm.

Question 16

What is the nucleolus and what is its function?

Answer 16

The nucleolus is a non-membrane-bound structure within the nucleus, composed of RNA. Its function is to produce ribosomal RNA (rRNA), a component of ribosomes.

Question 17

What are mitochondria and what is their primary function?

Answer 17

Mitochondria are membrane-bound organelles (double membrane with a folded inner membrane) in eukaryotes that are the main site of ATP (energy) production through cellular respiration. They are often called the “powerhouses” of the cell.
* the more active a cell is, the more mitochrondria it has.

Question 18

cellular respiration

Answer 18

cellular respiration is a reaction, in which glucose (C6H12O6) reacts with oxgen (6O2) in the presence of light energy resulting in carbon dioxide (6CO2, water (6H2O) and ATP.

Question 19

what is the endoplasmic reticulum and what are the differences between rough ER and smooth ER?

Answer 19

The ER is an interconnected system of membrane-enclosed channels. Rough ER has ribosomes attached and is involved in protein modification and transport. Smooth ER lacks ribosomes and is involved in lipid synthesis, detoxification, and storage.

Question 20

What is the Golgi apparatus and what is its main function?

Answer 20

The Golgi apparatus is a stack of membrane-lined channels involved in the processing, sorting, and packaging of proteins and lipids out of the cell. (to areas such as the plasma membrane and lysosomes)

Question 21

What are lysosomes and what is their function?

Answer 21

Lysosomes are membrane-bound vesicles containing digestive enzymes that break down macromolecules, non-functioning organelles (autophagy), and substances brought into the cell.

Question 22

What are peroxisomes and what is one of their key functions?

Answer 22

Peroxisomes are membrane-bound organelles containing enzymes that break down substances toxic to the cell. A key function is breaking down hydrogen peroxide (2H2O2 →2H2O+O2).

Question 23

What is the cytoskeleton and what are its main roles?

Answer 23

The cytoskeleton is a 3D structural framework in eukaryotic cells made of microtubules, intermediate filaments, and microfilaments. It provides support, determines cell shape, enables cell mobility, facilitates organelle movement, and moves chromosomes during cell division.

Question 24

What are centrioles and in which type of eukaryotic cell are they found? What is their role?

Answer 24

Centrioles are organelles found near the nucleus in animal cells, part of the cytoskeleton. They are involved in cell division.

Question 25

What are chloroplasts and in which type of eukaryotic cell are they found? What is their main function?

Answer 25

Chloroplasts are organelles found in plant and algae cells. They contain chlorophyll and are the site of photosynthesis, converting light energy into chemical energy.

Question 26

What is the vacuole in plant cells and what are its functions?

Answer 26

The vacuole in plant cells is a large, central membrane-bound organelle involved in the storage of nutrients and mineral salts, as well as waste disposal.

Question 27

what are features of chloroplasts

Answer 27

* they are relatively large cell organelles * they have a freen colour due to the presence of light-trapping pigments named chlorophylls * each chloroplast is enclosed in 2 membranes (inner and outer) * a 3rd membrane is present internally and this is folded to create an intricate internal structure consisting of many flattened membrane layers called grana(where the chlorophyll is located). * the region of fluid filled spaces between the grana are known as the stroma

Question 28

what are the cilia and flagella?

Answer 28

* cilia move in a wavelike motion to move the cell through a watery envirnoment, or to create water currents to move food and oxygen to specialised cells. 1. Cilia and flagella help unicellular eukaryotes move. Both have the same internal "9 + 2" microtubule structure. Flagella are long and used for movement; cilia are shorter, more numerous, and can move cells or fluids. In humans, cilia help clear mucus from the trachea and move eggs in the fallopian tubes.

Question 29

Endosymbiotic Theory – Lynn Margulis

Answer 29

* Proposed by Lynn Margulis in 1967. * Suggests mitochondria and chloroplasts were once free-living prokaryotes. * These were engulfed by a host cell and formed a mutualistic relationship. Evidence: * Own circular DNA * Bacterial-type ribosomes * Reproduce via binary fission * Similar size to bacteria * Chloroplasts resemble cyanobacteria, mitochondria resemble Rickettsia. * Now widely accepted and explains part of eukaryotic cell origin.