B2.2 Organelles + compartmentalization

Question 1

What do/are the organelles do?

Answer 1

Within most cells are highly specialized structures carrying out functions essential to the cell + organism. These specialized structures are called organelles. Organelles are adapted to their function. Most organelles are membrane bound, allowing compartmentalization with the cell. Not all parts of a cell are considered organelles.

Question 2

what does compartmentalization allow?

Answer 2

allows unique processes to proceed without interference from chemicals or reactions occurring nearby in the cell

Question 3

What is important in allowing reactions to occur without interference?

Answer 3

A cell has different reactions occurring in close proximity within it. Selectively permeable membranes are important in allowing these reactions/functions to occur without interfering with on another.

Question 4

Cell compartmentalization

Answer 4

The isolation of reactions = compartmentalization. The result of which is that cells work more efficiently than if all the reactions were mixed up together.

Question 4

what is reductionism?

Answer 4

the best way to focus on how cells work at molecular level is to reduce the cell to its component parts and study each part individually. This is an approach where we can study localized parts and reactions and develop understanding of overall reactions of the cell

Question 5

what are tools used to study cells

Answer 5

• Biochemical fractionation
• Electron microscopy
• Microscopes

Question 6

study of the cell involves a process called biochemical fractionation, what is biochemical fractionation?

Answer 6

Fractionation refers to the separation and isolation of specific chemicals and/or structures so that detailed research can be carried out. There are several different techniques -> each allows the separation of different parts of the cell. Centrifugation or cell fractionation allows the extraction of organelles from cells.

Question 7

What is the process of cell fractionation?

Answer 7

Ultracentrifuges are often used for this process. Cells are first mixed in a tube with substances that break down the cell membranes. The sample is then spun at high speeds to isolate the different components by size and shape. Larger and heavier cell components are able to be separated at lower speeds. Once separated, larger + heavier organelles are found at the bottom of the tube

Question 8

What is Chromatography?

Answer 8

this is very effective at isolating pure substances such as amino acids, proteins, carbohydrates and plant pigments. A mixture of molecules is placed in a separating medium. The molecules separate out depending on their size and the speed with which they travel through the medium. There are several different types of chromotagraphy; these include gel and ion exchange chromotography

Question 9

In column chromatography, what does in mean when each row has a different color?

Answer 9

The different colors indicate different substances that are isolated from the original compound in the test tubes

Question 10

What does gel electrophoresis do?

Answer 10

this separates molecules of different types by passing them through a gel using an electrical charge. The molecules are separated based on properties such as size and charge. This technique is commonly used in studies involving nucleic acids

Question 11

How are organelles separated from the rest of the cell?

Answer 11

Organelles are separated from the rest of the cell by a protective barrier, sometimes involving 2 membranes. This barrier is crucial as it allows the chemical reactions to take place in an organelle without interference from the rest of the cell

Question 12

Cell wall: organelle? general function?

Answer 12

It is not an organelle. This encloses and protects plant cells

Question 13

Cytoskeleton: organelle? general function?

Answer 13

It is not an organelle. This maintains the cell shape, anchors organelles, facilitates cell movement

Question 14

Cytoplasm: organelle? general function?

Answer 14

It is not an organelle. This is the region where most of the metabolic reactions in the cell occur

Question 15

Nucleus: organelle? general function?

Answer 15

This is an organelle. This is for the genetic control

Question 16

Vesicle: Organelle? General function?

Answer 16

This is an organelle. storage and support

Question 17

Ribosomes: organelle? general function?

Answer 17

This is an organelle. Protein synthesis

Question 18

Plasma membrane: organelle? general function?

Answer 18

This is an organelle. This regulates movement in and out of cell, transports materials to maintain the internal cell environment, cell recognition, and communicatio

Question 19

Cilia/flagella: organelle? general function?

Answer 19

This is an organelle. This controls movement

Question 20

Golgi apparatus: organelle? general function?

Answer 20

This is an organelle. This modifies and stores endoplasmic reticulum products, forms lysosomes and transport vesicles

Question 21

Mitochondria: organelle? general function?

Answer 21

This is an organelle. Cellular energy (ATP) production

Question 22

Chloroplasts: organelle? general function?

Answer 22

This is an organelle. Role = conversion of light energy into chemical energy

Question 23

Lysosomes: organelle? general function?

Answer 23

This is an organelle. Role = digest worn out organelles and debris, digest materials brought into the cell by endocytosis

Question 24

What is the advantage of eukaryotic cells having an nucleus?

Answer 24

allowed some of the important cell processes to take place more efficiently, compared to prokaryotic cells. mRNA must leave the nucleus in order to be transcribed

Question 25

What are the two cell processes that are responsible for the production of proteins?

Answer 25

Transcription and translation. In transcription, a DNA strand serves as a template or copy strand for the formation of messenger RNA. Translation occurs when ribosomes use the code carried by mRNA to produce a polypeptide/protein. Transcription occurs in nucleus while translation is carried out in the cytoplasm.

Question 26

what does the separation of transcription+translation do?

Answer 26

The separation of these two cellular processes allows post-transcriptional modification of mRNA to occur in the nucleus before translation happens in the cytoplasm. In prokaryotic cells there is no isolation of these 2 processes + mRNA can immediately come into contact with ribosomes and initiate translation without any modification occurring. The additional step of modification of mRNA in eukaryotes decreases the chances of errors happening in the production of polypeptides and proteins

Question 27

ALL Eukaryotic cells have compartments/organelles that are involved with...

Answer 27

- Energy production - Metabolism - Biosynthesis - Degradation

Question 28

does size+quantity of compartments vary?

Answer 28

Yes. They vary depending on the overall function of the cell in which they occur. EX. acinar cells (certain type of pancreatic cells) that specialize in the secretion of digestive enzymes. They have significantly enlarged endoplasmic reticulum, golgi apparatus, and granule storage compartments

Question 29

what has compartmentalization allowed?

Answer 29

It has allowed a division of labor within the cell, with specific tasks carried out by a single organelle or organelle-like structure. Enzymes can be kept in the areas where they will be most effective. Keeping reactions separate in different parts of the cell means that the metabolites and enzymes for each particular process can be concentrated in a particular area. This ensures that pathways run smoothly, can be easily controlled and do not interfere with eachother

Question 30

What do lysosomes participate in?

Answer 30

Lysosomes participate in the breakdown of wastes and cellular components that need to be replaced. This breakdown requires some potentially destructive enzymes that could cause severe damage to the cell if they were not isolated by the membrane.

Question 31

what is the result when endocytosis occurs?

Answer 31

When endocytosis occurs, the result is often a phagocytic vacuole. This vacuole is a means of protecting the cellular contents from potential damage when phagocytosis occurs

Question 32

what happens one the phagocytic vacuole is formed?

Answer 32

the phagocytic vacuole will move around in the cell unit it contacts a lysosome. The vacuole then fuses with the acidic lysosome, allowing inactivation and digestion of the threat.

Question 33

What is phagocytosis?

Answer 33

This plays a key role in defending cells against invading pathogens. This is a cellular process for ingesting and elimination particles larger than 0.5 micrometers in diameter/pathogens

Question 34

What challenges does compartmentalization present?

Answer 34

The fact that each area or organelle carries out one specific function means that the cell must develop a means of integrating all the separate functions. To accomplish this, some organelles are connected in a functional series, allowing the chemical pathways important to the cell to take place. Membrane pumps and carriers have evolved so that the products of one organelle can enter another, and important cell reactions can occur.

Question 35

What is cellular respiration?

Answer 35

this is the process by which glucose is used to produce adenosine triphosphate; this molecule then provides the energy needed for cell reactions. Respiration is a very complex series of chemical reactions, most of which occur in the mitochondrion.

Question 36

What is the mitochondrion?

Answer 36

An organelle found in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner part being folded inwards to from layers (Cristae). This is the site of aerobic respiration

Question 37

what adaptations has the mitochondrion undergone to produce ATP?

Answer 37

Several key adaptation that make it highly efficient at producing ATP through aerobic respiration. - Double membrane structure -> The inner membrane houses the electron transport chain and ATP synthase, while the outer membrane allows necessary molecules to enter, ensuring a controlled and efficient ATP production process. - Cristae - increased surface area for ETC proteins and ATP synthase - Selective permeability + transport proteins

Question 38

Overall equation for cellular respiration is;

Answer 38

C(6)H(12)+6O(2)->6C0(2)O+energy. This equation shows aerobic respiration because it includes oxygen as a reactant.

Question 39

why do all organisms carry out respiration?

Answer 39

All organisms must have the ability to produce ATP for energy, and therefore, all organisms carry out respiration

Question 40

what happens if there is a defect in any of the mitochondrial regions or structures?

Answer 40

This can cause ATP production to be diminished and even eliminated. Mitochondrial defects in children can lead to muscle weakness and affect mental development.

Question 41

Mitochondrion structure; Outer mitochondrial membrane, description + function

Answer 41

A membrane that separates the contents of the mitochondrion from the rest of the cell

Question 42

Mitochondrion structure; Matrix

Answer 42

An internal cytoplasm-like substance that contains the enzymes for the first stages of respiration that take place in the mitochondria

Question 43

Mitochondrion structure; Cristae

Answer 43

Tubular regions surrounded by membranes that increase the surface area for reactions that take place towards the end of respiration (oxidative phosphorylation)

Question 44

Mitochondrion structure; inner mitochondrial membrane

Answer 44

A membrane that contains the carriers and enzymes for the final stages of respiration (electron transport chain and chemiosmosis)

Question 45

mitochondrion structure; space between inner+outer membranes

Answer 45

a reservoir of hydrogen ions (protons), allowing a high concentration of protons.

Question 46

what is the chloroplast?

Answer 46

is a double-membrane organelle found in plant cells, it is responsible for photosynthesis. It contains chlorophyll, a green pigment that absorbs light energy to drive the conversion of carbon dioxide and water into glucose and oxygen. They have their own DNA and ribosomes, supporting the endosymbiotic theory.

Question 47

equation of photosynthesis

Answer 47

6CO(2)+12H(2)O+ light-> C(6)H(12)O(6)+6H(2)O+6O(2). In photosynthesis chemical bonds are made to produce carbon compounds. the raw materials of photosynthesis are carbon dioxide + water with light providing energy. Photosynthesis is essentially the reverse of respiration

Question 48

What types of processes are respiration and photosynthesis?

Answer 48

Respiration is a catabolic (breakdown, releases energy) process, whereas photosynthesis is anabolic (builds up, uses energy) process

Question 49

In what organisms does photosynthesis occur in?

Answer 49

In autotrophs. These organisms make their own food

Question 50

Chloroplast structure; extensive membrane surface area of the thylakoids

Answer 50

greater absorption of light by photosystems

Question 51

Chloroplast structure; small space (lumen) and low volumes of fluid within the thylakoids,

Answer 51

Faster accumulation of protons to create a concentration gradient

Question 52

Chloroplast structure; stroma region similar to cytoplasm of the cell and the matrix of the mitochondrion

Answer 52

Provides a region where the enzymes necessary for the Calvin cycle can work

Question 53

Chloroplast structure; double membrane on the outside

Answer 53

isolates the working parts and enzymes of the chloroplast from the surrounding cytoplasm

Question 54

What does the nuclear envelope do?

Answer 54

This is a double membrane, that provides an area where DNA can carry out its functions without being affected by processes occuring in other parts of the cell. The nucleus is bordered by a double membrane and is the region where DNA resides in.

Question 55

What do the nuclear pores do in the nuclear envelope?

Answer 55

The nuclear membrane has many pores that extend through both layers of the envelope. These nuclear pores allow ions and small molecules to diffuse between the nuclear material; the nucleoplasm and the cytoplasm. These pores also control the passage of mRNA, proteins, and RNA protein complexes in+out of the nucleus

Question 56

Where are the RNA-protein complexes produced

Answer 56

These RNA-protein complexes often become ribosomes. They are produced in a region of the nucleus -> the nucleolus

Question 57

the outer membrane of the nuclear envelope is continuous with ...

Answer 57

the ER of the cytoplasm, an even shares some functions with the ER. Ribosomes are often seen attached to the other nuclear membrane, and this membrane can also form vesicles just like the ER

Question 58

What does the inner membrane of the nuclear membrane interact with?

Answer 58

it interacts with the inactive form of DNA-> called Chromatin. Which occurs within the nucleolus. This is important in maintaining the shape of the nucleus

Question 59

What is chromatin?

Answer 59

This is an elongated form of DNA arranged around proteins. Studies indicates that chromatin affects the function of DNA. Changes in chromatin can cause changes in gene expression (these are called epigenetic changes)

Question 60

What feature of the nuclear envelope is seen during the cell division processes, mitosis and meiosis?

Answer 60

Early in both processes the nuclear membrane breaks down to allow movement of the DNA structures. generally, the nuclear envelope breaks apart, becoming vesicles freely circulating in the cytoplasm. Once the DNA is correctly positioned at the conclusion of the two processes, these vesicles attach to the surface of the highly condensed chromosomes and undergo a series of complex changes to reform the nuclear envelope

Question 61

What are ribosomes?

Answer 61

these are cytoplasmic organelles found in both prokaryotic and eukaryotic cells. Ribosomes are composed of proteins and a specific type of RNA called ribosomal RNA (rRNA). All ribosomes produce ribosomes. They are responsible for protein synthesis

Question 62

what is the difference between ribosomes in prokaryotes and eukaryotes?

Answer 62

ribosomes in prokaryotes are slightly smaller than those of eukaryotic cells

Question 63

what are ribosomes composed of?

Answer 63

They are composed of 2 subunits; large ribosomal subunit (includes a P and an A site), and a small ribosomal subunit (mRNA binding site, where mRNA is positioned for translation)

Question 64

To what can ribosomes be attached?

Answer 64

They can be attached to rough ER, or they may be free in the cytoplasm of the cell.

Question 65

How are free ribosomes different than membrane-bound ribosomes?

Answer 65

They produce different proteins. Free ribosomes produce protein that are used within the cell, such as in the supporting cytoskeleton of the cells, they are also used in nucleus, mitochondria and in other organelles not derived from the cell's inner membrane system. Ribosomes that are membrane-bound produce proteins that are transported through the ER and often are exported from the cell

Question 66

Which organelles use membrane-bound ribosomes or free ribosomes?

Answer 66

Membrane-bound ribosomes -> Produce proteins for secretion or membrane-bound organelles Free ribosomes-> Produce proteins for the cytoplasm, nucleus, mitochondria, and other non-membrane-bound organelles.

Question 67

What proteins are produced by membrane-bound ribosomes and then get sent to golgi apparatus?

Answer 67

Proteins called secretory proteins. Once produced they get sent to the golgi apparatus, where they are properly packaged for cellular exit. Secretory protein examples = Hormones and enzymes

Question 68

What does the golgi apparatus consist of?

Answer 68

usually consists of flattened sacs. There can be as few as one in single-celled organisms, and more than 20 in some animal cells. These stacks of flattened sacs are called cisternae

Question 69

When are the sacs (golgi apparatus) especially numerous?

Answer 69

they are especially numerous in cells that are engaged in producing and secreting substances.

Question 70

What do the opposite sides mean on the golgi apparatus (Cis + Trans side)?

Answer 70

One side of the stack is located near the ER (this is the cis side), the other side is directed towards the plasma membrane (the trans side). Protein or lipid-filled transport vesicles are received on cis side from either ER. As the protein/lipid moves through the cisternae they are modified so that they can carry out the specific function needed. Once modified the final product is then packaged into vesicles that depart from the trans side. Often modification of the substance includes the attachment of a signal chemical that directs the destination of the product.

Question 71

What is the golgi apparatus?

Answer 71

is a membrane-bound organelle that modifies, sorts and packages proteins and lipids received from the ER for secretion or delivery to other parts of the cell

Question 72

What happens with the vesicles that leave from the trans side of the golgi apparatus

Answer 72

Some vesicles may become lysosomes within the cell, and others may return to the ER. Many will combine with the plasma membrane and go through the process of exocytosis, resulting in the secretion of the substance out of the cell

Question 73

What are vesicles?

Answer 73

are small membrane-bound sacs in which various substances are transported or stored in the cell. Examples of vesicles -> lysosomes; contains enzymes necessary for cellular digestion and also for destroying defective or damaged organelles, transport vesicles; which move molecules within the cell

Question 74

What are Clathrins?

Answer 74

they are proteins in the cell membrane that anchor certain proteins to specific sites, especially on the exterior plasma membrane in receptor-mediated endocytosis. The clathrin proteins line coated pits, allowing the receptors to bind to specific molecules. When an appropriate collection of molecules occurs in the lined pit, the pit deepens and will eventually seal off, forming a vesicle. Because different cells need to take in different molecules, they have specific receptors on their surface

Question 75

What is the advantage of receptor-mediated endocytosis?

Answer 75

Is that it is quite selective and efficient, especially compared to ordinary endocytosis