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The Cell (Part III)
“Function and structure of
organelles in eukaryotic cells”

Professor: Bárbara López

Table of contents
Endoplasmic reticulum: RER y SER
Golgi apparatus
The Ribosomes
The Mitochondria
Lysosomes
Peroxisomes
Plant cell structures: Chloroplasts, large vacuole and
cell wall
Quiz III: Structure and function organelles
Answers Quiz III

Organelles of the cell
Endoplasmic reticulum (ER): Formed by rough endoplasmic
reticulum (RER) and smooth endoplasmic reticulum (SER)
...
Has
ribosomes attached to its outer surface
...

Assembly and modification of proteins entering the
endoplasmic reticulum (ER)
...

Function
Lipid synthesis
Involved in the detoxification of the organism (degradation
of toxic substances and/or drugs such as alcohol)
Involved in calcium storage
In liver cells: REL is found in very abundant form
...
A cis face (Entrance): where vesicles enter from the
ER, which contain proteins and lipids
...
An intermediate or central tank
3
...


Golgi apparatus
Function
Reception and chemical modification of proteins and lipids
...

b) Exported outside the cell
...


Figure 6: Schematic representation of the
Golgi apparatus
Rough
endoplasmic
reticulum
Lisosome

Vesicle
transition

Dictyosoma

Vesicle
secretion

Ribosomes
They are small spherical structures made up of two
ribosomal ribonucleic acid (rRNA) subunits and proteins
...

They are present in all cells, can be located free in the
cytoplasm or attached to the endoplasmic reticulum
forming the RER (Rough endoplasmic reticulum), they are
also found in Chloroplast and mitochondria
...


1
...
The molecule of mRNA contain
sequence de three nucleotides called codon encoding a specific
amino acid
...
- The mRNA is anchored to the minor subunit of the ribosome
and in this same region binds the tRNA that carries the amino
acids and together they form a complex with the minor and major
subunit of the ribosome and transduction begins, which is the
process by which the mRNA is decoded to specify the amino
acid sequence to form a new protein
...
(figure 8)
It is the site where most of the cellular respiration
reactions occur and where energy is obtained from glucose
or lipids
...

The mitochondrial inner membrane folds to form
mitochondrial ridges
...


Figure 8: Schematic representation of
the components of mitochondria
...


The inner mitocondrial membrane is more selective
and strict in the entry of molecules that can pass through it
...


Function of mitochondria
The main function of mitochondria is to generate energy
(ATP) from glucose through the cellular respiration reaction:
C6H12O6 +
(Glucose)

602

6CO2

(oxygen)

(oxigen
dioxide)

+

6H20 + ATP
(water)

(Adenoxin
trifosfato)

Mitochondria provide the energy needed for all cellular
activities and processes that require energy or ATP
...
Examples include
muscle, heart and liver cells, to name a few
...
(figure 9)
Function
1
...

2
...

3
...


Figure 9 : Structure of the lysosome

Membrane
Hydrolytic
enzymes

Proteins

Peroxisomes
They are vesicles with
membranes and enzymes
inside (figure 10)

Function
It participates in
oxidation reactions in the
degradation of fatty acids
...


Crystalline
nucleus

Lipid
bilayer

Figure 10: Structure of the
peroxisome

Plant cell structures
Plant cell

1
...

2
...


Chloroplast
Cell
wall

Vacuole

Plant cell structures
3
...

(Site where
photosynthesis occurs)

Outer
membrane

Inner
membrane

Intermembrane
space

Stoma

Grana
(Thylakoids
stack)

Thylakoids

Quiz III : The Cell (Part III)
1
...

b) Membrane protein synthesis
...

d) Lipid synthesis
...
- These are functions of the smooth endoplasmic reticulum (SR), except:
a) Involved in calcium storage
...

d) Involved in the degradation of toxic substances and / or drugs
...
- ´´The Reception and chemical modification of proteins and lipids´´ is a function of:
a) Rough endoplasmic reticulum (RER)

b) Ribosomes
c) Golgi apparatus
d) Smooth endoplasmic reticulum (SER)

4
...
- In which of the following cell structures are ribosomes not found?
a) Chloroplasts
b) mitochondria
c) Rough endoplasmic reticulum (RER)
d) Lysosomes
6
...
- The composition of a eukaryotic ribosome is:
a) A minor subunit 40s and a major subunit 60s
b) A minor subunit 30s and a major subunit 50s
c) A minor subunit 30s and a major subunit 60s
d) A minor subunit 40s and a major subunit 50s

8
...
- The function of ribosomes is:
a) Lipid synthesis
b) Protein synthesis
c) Nucleic acid synthesis
d) Carbohydrate synthesis

10
...
- In protein synthesis, the molecule that brings amino acids to the ribosome is:
a) mRNA
b) tRNA
c) rRNA
d) ATP

12
...

b) A sequence of two nucleotides that codes for a particular amino acid
...

d) A sequence of three nucleosides that codes for a particular amino acid
...
- The cell wall gives the plant cell:
a) Barrier that gives porosity
b) Barrier that gives electric charge
c) Barrier that gives movement
d) Barrier that gives rigidity and protection

14
...
- ´´Maintain cell shape and size through turgor in plant cell´´ :
a) The mitochondria
b) The wall cell
c) The vacuole
d) The plasma membrane

Answers Quiz III (The cell part III)
1D
2C
3C
4B
5D
6C
7A
8B
9B
10 C
11 B
12 A
13 D
14 B
15 C



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