Introduction to biomedical sciences
2015-09-02
Basic Biochemistry and
Cell Biology
The cell, the basic unit for all life
Structure and
Function
of the Human Body,
10th Ed.
3rd Chapter
(entire chapter, except
the section about the
microscope)
The Cell, the basic unit
Jan-Olov Höög
1
Introduction to biomedical sciences
2015-09-02
Genomes
Species
Genome size
(Mb)
Number of
genes
Year
Haemophilus
influenze
1.8
1,743
1991
Escherichia
coli
4.6
4,285
1996
Saccharomyces
cerevisiae
12.1
6,266
1996
Caenorhabditis
elegans
97
19,000
1998
Arabidopsis
Thaliana
125
25,500
2001
Drosophila
melanogaster
110
13,500
2000
Homo sapiens
3,200
40,000
23,762
ca 25.000
2001
2004
The Central Dogma
DNA  RNA  Protein
Proteins as enzymes, biological catalysts, are
required in every step of these processes.
DNA is transcribed into RNA that is further
translated into proteins. DNA itself can be
replicated.
Jan-Olov Höög
2
Introduction to biomedical sciences
2015-09-02
The Cell – the smallest living unit
Structural
Organisation
• Atom
• Molecule
• Cell
• Tissue
• Organ
• Organ
system
• Organism
Jan-Olov Höög
3
Introduction to biomedical sciences
2015-09-02
The Cell
Subcellular Component
The cell membrane, or plasma
membrane, surrounds the
cytoplasm of a cell. This
membrane serves to separate and
protect the cell from its
surrounding environment and is
made mostly from a double layer
of phospholipids.
Jan-Olov Höög
4
Introduction to biomedical sciences
2015-09-02
The Cell Membrane
The cell membrane is made mostly from a double layer of
phospholipids, including membrane proteins and carbohydrates
Cell Organelles
A cell's information center, the cell
nucleus houses the cell's
chromosomes, and is the place where
almost all DNA replication and RNA
synthesis (transcription) occur. The
nucleus is spherical and separated from
the cytoplasm by a double membrane
called the nuclear envelope .
Jan-Olov Höög
5
Introduction to biomedical sciences
2015-09-02
Cell Organelles
Mitochondria are self-replicating
organelles that occur in various
numbers, shapes, and sizes in the
cytoplasm of all eukaryotic cells.
Mitochondria play a critical role in
generating energy in the eukaryotic
cell by oxidative phosphorylation.
Cell Organelles
The endoplasmic reticulum (ER) is
a transport network for molecules
targeted for certain modifications
and specific destinations. The ER
has two forms: the rough ER,
which has ribosomes on its
surface that secrete proteins into
the ER.
Jan-Olov Höög
6
Introduction to biomedical sciences
2015-09-02
Cell Organelles
The ER has two forms: the smooth
ER, which lacks ribosomes. The
smooth ER plays a role in calcium
sequestration and release as well as
in lipid synthesis.
Cell Organelles
The primary function of the Golgi
apparatus is to process and package
the macromolecules such as proteins
and lipids that are synthesized by the
cell.
Jan-Olov Höög
7
Introduction to biomedical sciences
2015-09-02
Cell Organelles
Lysosomes contain digestive
enzymes (acid hydrolases). They
digest excess or worn-out
organelles, food particles, and
engulfed viruses or bacteria.
Cell Organelles
Peroxisomes have enzymes that
rid the cell of toxic peroxides.
The cell could not house these
destructive enzymes if they were
not contained in a membranebound system.
Jan-Olov Höög
8
Introduction to biomedical sciences
2015-09-02
Cell Organelles
Vesicles transport e.g. proteins
out of the cell after they are
modified
Cell Organelles
The ribosome is a large complex of RNA
and protein molecules. They act as an
assembly line where RNA from the
nucleus is used to synthesise proteins
from amino acids. Ribosomes can be
found either floating freely or bound to
the rough endoplasmatic reticulum.
Cytoplasm is the floating mass between
the membrane and the nucleus.
Jan-Olov Höög
9
Introduction to biomedical sciences
2015-09-02
Different cell types
• The human body is build up of
about 200 different cell types
(altogether ca. 1013 cells)
• The cells are the basic units
forming tissues (e.g. muscle and
nerve tissues). The tissues are
forming the organs (e.g. stomach
and brain).
Different cell types (cont.)
•
•
•
•
•
•
•
nerve cells
epithelial cells
fat cells
muscle cells
erythrocytes
sex cells
…
• For a list of >100 different cells, see
https://en.wikipedia.org/wiki/Category:Human_cells
Jan-Olov Höög
10
Introduction to biomedical sciences
2015-09-02
Stem cells
• Stem cells are undifferentiated
biological cells that can
differentiate into specialized
cells and can divide (through
mitosis) to produce more stem
cells.
• Adult stem cells are frequently
used in medical therapies, for
example in bone marrow
transplantation.
Jan-Olov Höög
11
Introduction to biomedical sciences
2015-09-02
The Minimalistic Cell
(in theory 127 genes)
Jan-Olov Höög
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