The nature of life. Cell structure and function

1. Lecture: The Nature of life. Cell structure and function.

ZAPOROZHYE STATE MEDICAL UNIVERSITY
DEPARTMENT OF MEDICAL BIOLOGY
Lecture:
The Nature of life. Cell
structure and function.
Composed by
Doctor of Philosophy
Popovich A. P.
[email protected]
Zaporozhye - 2016

2. QUESTIONS

-The main characteristics of Living Things
- Levels of organization
- Pro and Eukaryotes
- Cell structure and functions

3. Characteristics of Living Things

Living things share several characteristics. These
characteristics include the following:
Living things are made up of units called cells.
Living things reproduce.
Living things are based on a universal genetic code.
Living things grow and develop.
Living thins obtain and use materials and energy.
Living things respond to their environment.
Living things maintain a stable internal environment.
Taken as a group, living things change over time.

4. Levels of Organization

Biosphere
The part of Earth that contains all
ecosystems.
Ecosystem
Community and its nonliving
surrounding.
Community
Populations that live together in a
defined area.
Population
Group of organisms of one type that
live in the same area.
Organism
Indiviclual living thing.
Groups of Cells
Tissues, organs, and organ systems.
Cells
Smallest functional unit of lafe.
Molecules
Groups of atoms; smallest unit of
most chemical compounds.

5.

The largest and most complex level
is the biosphere. The smallest
level is the molecules that make
up living things.

6. The Cell Theory states the following:

All living things are composed of cells.
Cells are the basic units of structure and
function in living things.
New cells are produced from existing cells.

7.

8. Differences between prokaryotic and eukaryotic cells.

Feature
Prokaryotic cell
Eukaryotic cell
Cell wall
Present in most but not in
all cells
Present in plant and fungal
cells only
Plasma membrane
Present
Present
Nucleus
Absent
Present
Genetic material
Circular or linear, double –
stranded DNA: genes are
not interrupted by introns
Linear, double – stranded
DNA: genes frequently
intterrupted by intron
sequences, especially in
higher eucaryotes.
Cellular organelles
Absent, except ribosomes
Present
Respiration
Many strict anaerobes
(oxygen fatal)
All aerobic, but some
facultative anaerobes by
secondary modifications

9. Membranous Organells ER

It is a network of membrane – limited channels,
which continues with the flasme membrane and
the nuclear envelops.
Provididing
A large surface area for chemical reactions
A pathway for the transport of material the cell
Producing
Proteins, especially enzymes (rough ER)
Lipids and steroids (smouth ER)
Collecting and storing synthesized material

10.

11. GOLGI APPARATUS (dictyosome)

It consists of flattened membranous sacsciternae –
looking like a stack of pita bread. A Golgi stack has a
polarity: the cis face and the trans face.
The cis face receives the products of the ER. These
products are usually modified during their transit from the
cis pole to the trans pole of the Golgi.
The trans face gives rise to vesicles, which pinch of and
travel to other sites.
Its functions include:
Producing glycoproteins, secretory enzymes,
carbohydrates.
Transporting and storing lipids.
Forming lysosomes, acrosome.

12.

13. MITOCHONDRIA

They are bounded by a double membrane, the
outer of which controls the entry and exit of
chemicals.
The inner membrane is folded inwards, giving rise
to extensions called cristae. They inerease the
surface area on which respiratory processes
take place. The remainder of the motochondrion
is the matri, which contain frotein, lipids and
DNA.
Mitochondria are the sites of cellular respiration.

14.

15. VACUOLES and VESICLES

VACUOLES and VESICLES are membrane –
bounded sacs within the cell. Vacuoles have
various functlons:
Food vacoules – for inrtacellular Ligestion.
Contractole vacuoles – pump excess water out
of the cell
Central vacuole enclosed by a membrane
called tonoplast can hold important organic
compounds inorganic ions, pigments in the plant
cells.

16.

17. PLASTIDS

They can be found in the plant cells. There
are three types of plastids: chloroplasts,
chromoplasts, amyloplasts.
In higher plants chloroplasts are
bounded by a double membrane.

18. THE NUCLEUS

It is bounded by a double membrane – the
nuclear envelope with many pores. The
cytoplasm – like material within the
nucleus is callednucleoplasm. It contains
chromatin and nucleolus.
The nucleus contains the genetic material
of a cell, controls it activities,
manufactures ribosomes and RNA.

19.

20. LYSOSOMES

They are membrane – bounded
sacs of hydrolytic enzymes that
the cell uses to digest material
which the cell consumes from the
environment, to digest part of the
cell (autophagy).

21.

22. PEROXISOMES (microbodies)

Small spherical membrane – bounded
bodies that contain a number of
metabolically important enzymes, in
particular the enzyme catalase, which
catalyses the break down of hydrogen
peroxide.

23. NON-MEMBRANOUS STRUCTURES

RIBOSOMES
They are made up of one large and one
small subunit, and comprise RNA, known
as ribosomal RNA, and protein. They
perform the protein synthesis.

24. CENTROSOME

It is a region near the nucleus of the
animal cell which contains a pair of
centrioles, each composed of nine sets of
triplet microtubules arranged in a ring.
Centrosome helps to organize the spindle
during cell division.

25. The cytoskeleton

The cytoskeleton, a network of fibers extendind
throughout the cytoplasm. It plays a major role in
organizing the structures and activities of the
cell. The three main types of fibers make up the
cytoskeleton:
Mocrotubules – are the thickest and
constructed from a protein – tubulin;
Microfilaments – are the thinnest, also called
action filaments;
Intermediate filamets – are fibers with
diameters in a middle range.