Majmaah University Preparatory Year Program Colleges of Medicine Biology Course Title: Biology for Premedical Students Course Code: Biol. 126 Credit Hours: 3 (2+1) Prerequisites : None

Required Text(s) Campbell, N. A. and Reece, J. B. (2005). Biology (6 th edition). Pearson Education. Inc. USA.

What is Biology?  Biology is the Science of Our Lives.  Biology literally means "the study of life " "the study of life ".

Some Branches of Biology O Cell biology: The study of the cell as a complete unit, and the molecular and chemical interactions that occur within a living cell. O Embryology: The study of the development of embryo. O Entomology: The study of insects

O Ecology: The study of interactions among organisms and their environment. O Microbiology: The study of microscopic organisms (microorganisms) and their interactions with other living things. O Parasitology: The study of parasites and parasitism.

O Anatomy: The study of form, in plants, animals, and other organisms, or specifically in humans.  Histology: The study of cells and tissues ( a microscopic branch of anatomy).  Ethology: The study of animal behavior.  Genetics : the study of genes and heredity.

O Molecular Biology: The study of biology and biological functions at the molecular level. O Neurobiology: The study of the nervous system. O Pathology: The study of diseases, and the causes, processes, nature, and development of disease.

 Epidemiology: The study of factors affecting the health and illness of populations.  Biochemistry: The study of the chemical reactions required for life to exist and function, usually a focus on the cellular level.  Bioinformatics: The use of information technology for the study, collection, and storage of genomic and other biological data

What Is Life? Growth and development Metabolism Homeostasis Movement Response to stimuli Reproduction Evolution and adaptation

Characteristics of living things Living things have a variety of common characteristics: Organization: Living things exhibit a high level of organization, with multicellular organisms being subdivided into cells, and cells into organelles, and organelles into molecules, etc.

Levels of organization 1. Biosphere Land – water – atmosphere (inhabited by life). 2. Ecosystem Living thing and non-living thing with which life interacts in particular area (forests or oceans or deserts). 3.Community living different species in particular ecosystem. 4.Population one species. 5.Organism one individual (Body). 6. Organs group of tissues 7. Tissues groups of cells 8. Cells 9. Organelles 10. Molecules

Homeostasis: is the maintenance of a constant (yet also dynamic) internal environment in terms of temperature, pH, water concentrations, etc. Much of our own metabolic energy goes toward keeping within our own homeostatic lim its. Adaptation: Living things are suited to their mode of existence.

O Reproduction and heredity: -Cells must have some way of reproducing, whether that involves asexual (no recombination of genetic material) or sexual (recombination of genetic material). -Most living things use the chemical DNA (deoxyribonucleic acid) as the physical carrier of the genetic information. -Some organisms, such as retroviruses (of which HIV is a member), use RNA (ribonucleic acid) as the carrier.

Growth and development:  Even single-celled organisms grow O Multicellular organisms pass through a more complicated process of differentiation and organogenesis.

O Energy acquisition and release: One view of life is that it is a struggle to acquire energy (from sunlight, inorganic chemicals, or another organism), and release it in the process of forming ATP ( adenosine triphosphate ). O Detection and response to stimuli ( both internal and external).

O Interactions: Living things interact with their environment as well as each other. The various types of symbioses (organismal interactions with each other) are examples of this. eg;gut flora

Cell Theory 1- All organisms are composed of one or more of cells. 2- Cell is the basic unit of life. 3- The new cell arises only from pre-existing cell. pre-existing cell.

The Cell The Organism’s Basic Unit of Structure and Function ProkaryoticProkaryotic EukaryoticEukaryotic Types of cells of cells Micro-organisms All other forms of life بدائية متقدمة

تركيب الخلايا بدائية النواة Prokaryotes

Generalized Prokaryote Capsule Cell Wall Plasma Membrane Cytosol Nucleoid DNA Flagellum Plasmid DNA

Typical shapes of bacteria Most bacteria retain a particular shape ; a few are polymorphic

Bacterial Shape and Arrangement

24 VirusesViruses Page 328

Characters of viruses O Viruses are much smaller than bacteria. O Virus is about 20nm in diameter. O Viruses are not cells. O A virus is a genome enclosed in a protective coat

26 Genome ( DNA/RNA ) Protein coat () Protein coat (capsid) Virus is a genome enclosed in a protective coat

27  A protein shell that encloses the viral genome.  It is rode-shaped, helical, polyhedral or more complex.  Capsomeres: Are the protein units that form capsid. A- Capsid الجدار الفيروسى Page 329, 330 Capsomeres ( proteins ) Capsid Sometimes further rapped يُغَلَّف in a membranous envelope (Viral envelope الغلاف الفيروسى ), eg. Influenza virus. viral envelope Membranous envelop ( viral envelope )

28 viral envelopes  Some viruses have viral envelopes, membranes cloaking their capsids.  These envelopes are derived from the membrane of the host cell. Fig. 18.2c, Page 330 B- Envelop الغطاء الفيروسى

29 Viral Genome: (Hereditary material المادة الوراثية) Viral genomes may consist of: - double-stranded DNA (dsDNA), - single-stranded DNA (ssDNA), - double-stranded RNA (dsRNA), - single-stranded RNA (ssRNA). depending on the specific type of virus. The viral genome is usually organized as a single linear or circular molecule of nucleic acid. four genesseveral hundred The smallest viruses have only four genes, while the largest have several hundred.

30 - DNA enclosed in a protein coat ( sometimes, membranous envelop also ) - Can be crystallised يتبلور Key CharactersViruses Key Characters Viruses - Reproduced only within a living host cell - Reproduced only within a living host cell ( obligate parasitism تطفل إجبارى ). - They lack يفتقد enzymes for metabolism - Have no ribosomes for making their own proteins - Each type of virus infects a limited range of host cells (host range مدى الإصابة ) Human cold AIDS Most viruses of eukaryotes attack specific tissues. eg. Human cold viruses infect only the cells lining the upper respiratory tract, and AIDS virus binds only to certain white blood cells (Immune system).

Eu: True Karyon: Nucleus Animal Cell Plant Cell Eukaryotic Cell

ميتوكوندريا غشاء بلازمى جهاز جولـﭽـى ريبوسوم الهيكل الخلوي جسم مُحلل جسم مركزي سوط حركي الشبكة الإندوبلازمية النواة المادة الوراثية نوية الجدار النووى حلمات دقيقة

33 Eukaryotic Cells Not in plant cell: -Lysosomes - centrosomes with centrioles - flagella Not in plant cell: -Lysosomes - centrosomes with centrioles - flagella

34 Generalized Cell Animal Cell Plant Cell Nucleus Golgi Mitochondria Endoplasmic Reticulum Centrioles Chloroplasts

characters Animal cell Plant cell O Absent O One or more small O Absent O only cell membrane O Present O One, large central vacuole O Present O cell wall and a cell membrane O Absent Cell wall Vacuole Chloroplast Plasma Membrane Lysosomes Centrioles Flagella

 All cells are surrounded by a plasma membrane غشاء بلازمى.  The semi-fluid substance المادة النصف سائلة within the cell is the cytosol, السيتوبلازم containing the cell organelles عِضيات الخلية.  All cells contain chromosomes which have genes in the form of DNA.  All cells also have Ribosomes, tiny organelles عضيات صغيرة that make proteins using the instructions التعليمات contained in genes.  All cells are surrounded by a plasma membrane غشاء بلازمى.  The semi-fluid substance المادة النصف سائلة within the cell is the cytosol, السيتوبلازم containing the cell organelles عِضيات الخلية.  All cells contain chromosomes which have genes in the form of DNA.  All cells also have Ribosomes, tiny organelles عضيات صغيرة that make proteins using the instructions التعليمات contained in genes. Similarities Similarities أوجه التشابه

 A major difference الفرق الأساسى between prokaryotic and eukaryotic cells is the location of chromosomes موضع الصبغيات  In an eukaryotic cell, chromosomes are contained in a true nucleus ( النواة ).  In a prokaryotic cell, the DNA is concentrated in the nucleoid ( شـبه نواة ) without a membrane ( بدون غـشاء ) separating it from the rest of the cell.  In prokaryotic cell, DNA is a single strand ( أحادى الشريط ) or double strand ( ثنائى الشريط ) DNA. But in eukaryotic cell, DNA is double strand.  A major difference الفرق الأساسى between prokaryotic and eukaryotic cells is the location of chromosomes موضع الصبغيات  In an eukaryotic cell, chromosomes are contained in a true nucleus ( النواة ).  In a prokaryotic cell, the DNA is concentrated in the nucleoid ( شـبه نواة ) without a membrane ( بدون غـشاء ) separating it from the rest of the cell.  In prokaryotic cell, DNA is a single strand ( أحادى الشريط ) or double strand ( ثنائى الشريط ) DNA. But in eukaryotic cell, DNA is double strand. Differences Differences أوجه الاختلاف