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The Cell (Part II)
´´Main parts of a eukaryotic type
cell´´

Professor: Bárbara López

Table of contents
Main parts of a eukaryotic type cell
The cytoplasm
Cytoskeleton: microtubules, intermediate filaments and
Microfilaments
...

It is located between the nuclear envelope and the
plasma membrane
...

There is a structure that supports the Cytoplasm, the
cytoskeleton, which will be describes below
...
(Figure 2)
Formed by :
Microtubules: made up of proteins called tubulins
...
They are also
involved in cell division, movement of cilia and flagella
...
(Diameter: 8 a 12 nm) Capable of resisting high
mechanical stresses
...
(Diameter: 6 a 7 nm)
Microfilaments are involved in the contraction process of
muscle cells
...

Involved in the intracellular transport of substances,
movements of organelles within the cytoplasm and movements
of the cell itself
...

The components that are part of the nucleus (figura 3):
1
...
-Plasma membrane
3
...
-Chromatin
Function of the nucleus
It contains the genetic material of the organism which is
stored in DNA molecules, regulates its functions and is
considered the genetic control centre of cellular activities
...

The nucleolus is not bounded by a cell membrane
...


Nuclear envelope
It confines the nucleus and separates the nuclear
contents from the cytoplasm
...

Function
Communication and transport of materials between
the nucleus and the cytoplasm
...


It Contains biomolecules: Proteins, enzymes, DNA
nucleotides, RNA, ions and water
...


Chromatin
It is the genetic material found as DNA molecules
(Ácido Desoxirribonucleico) and which is associated with
RNA molecules and proteins
...

Chromosomes can only be visualised under the
microscope, when the cell is in cell division
...

Heterochromatin is the more compacted chromatin and
euchromatin is less menos condensed or more lax
...


The plasma membrane
It is a phospholipid bilayer containing in its structure
cholesterol and proteins, molecules which are irregularly
distributed through the membrane
...

The membrane is a structure highly dynamic, because its
molecules are in constant movement
...

It is selective permeability, meaning that certain substances
can pass through the membrane and others cannot
...

- Hydrophilic means chemically affinity for water
...

The head of the phospholipid corresponds to the hydrofilic
part which is formed by the phosphate group and glycerol and
the hydrofobic part formed by the composition of fatty acids
...


Figura 4: Cross-section of the plasma
membrane
OUTER PART
GLYCOPROTEIN
OF THE
CHOLESTEROL
WHOLEMEAL
MEMBRANE

GLYCOLIPIDS

PROTEIN

PHOSPHO
LIPID
BILAYER

HYDROPHOBIC
PART (Fatty
acids)

INNER PART OF
THE MEMBRANE
(Phosphate group
and glycerol)

PERIPHERAL
PROTEIN

HYDROPHILIC
PART

The plasma membrane
Main functions
The plasma membrane defines and limits the cell
...

Recognition and transduction of external signals
...


Quiz II : The Cell (Part II)
1
...
- The human skeleton is a structure that provides support to the human body
...
- They are components of the cell nucleus, except:

a) Peroxisomes
b) Chromosomes
c) Nucleolus
d) Nucleoplasm

4
...
- The fluid Mosaic model of the plasma membrane, proposed by Singer and Nicholson
in 1972, mentions the term mosaic fluidity which refers to:

a) That both lipids and proteins can move freely and vertically across the membrane
...

c) That both lipids and proteins can move freely and laterally across the membrane
...
- These are functions of the plasma membrane, except:
a) Transport of substances between the nucleus and the cytoplasm
...

c) Recognition and transduction of external signals
...


7
...

b) The Hydrophobic part repels water, and the hydrophilic part has an affinity for water
...

8
...
- Consisting of globular proteins called actins and are involved in the contraction
process of muscle cells:

a) Microtubules
b) Microfilaments
c) Intermediate filaments
d) None of the above

10
...
- These are molecules of a protein nature found in the plasma membrane, except:
a) Peripheral protein
b) Glycolipids
c) Wholemeal protein
d) Glycoprotein
12
...
- Of the following statements regarding chromatin, one is false:
a) Chromatin can be packaged to form chromosomes
...

c) Heterochromatin is the more compacted chromatin and euchromatin is less menos
condensed or more lax
...

14
...
:
a) Microtubules

b) Microfilaments
c) Intermediate filaments
d) None of the above
15
...
They are also involved in cell division, movement of cilia and flagella:

a) Microtubules
b) Microfilaments
c) Intermediate filaments
d) None of the above

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



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