Introduction to cells

INTRODUCTION TO CELLSIB BIOLOGY – 2016 SYLLABUS

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CELL THEORY

• ACCORDING TO CELL THEORY, ALL LIVING THINGS ARE COMPOSED OF CELLS

• HUMANS, E. COLI, SPIDERS, ALGAE – ALL OF THEM HAVE CELLS

• CELLS ARE CONSIDERED THE BASIC BUILDING BLOCKS OF LIFE

UNICELLULAR ORGANISMS

• ORGANISMS CONSISTING OF ONLY ONE CELL CAN CARRY

OUT ALL THE FUNCTIONS OF LIFE

• THESE INCLUDE BACTERIA AND PROKARYOTIC CELLS

• THE MAIN FUNCTIONS OF LIFE INCLUDE: METABOLISM,

RESPONSE TO CHANGING ENVIRONMENTS, HOMEOSTASIS,

GROWTH, REPRODUCTION AND NUTRITION

SURFACE AREA TO VOLUME RATIO

• CELLS MOVE THEIR NUTRIENTS, PROTEINS AND OTHER MOLECULES THROUGH THEIR

CYTOPLASM USING DIFFUSION

• AS CELLS GET LARGER, IT TAKES LONGER FOR NEEDED MOLECULES TO DIFFUSE

• THE RATIO CREATES A LIMIT ON THE POTENTIAL SIZE OF CELLS

𝑹𝒂𝒕𝒊𝒐 =𝑺𝒖𝒓𝒇𝒂𝒄𝒆 𝑨𝒓𝒆𝒂

𝑽𝒐𝒍𝒖𝒎𝒆

EMERGENT PROPERTIES

• ON THEIR OWN, INDIVIDUAL CELLS CAN PERFORM CERTAIN FUNCTIONS

• HOWEVER, WHEN THEY WORK TOGETHER IN A MULTICELLULAR

ORGANISMS, THE TEAMWORK LEADS TO NEW PROPERTIES

• THEY ARE CALLED ‘EMERGENT PROPERTIES’

• FOR EXAMPLE, CELLS IN THE HEART WORK TOGETHER TO CREATE A

PUMP: A SINGLE CELL COULD NOT PUMP BLOOD ON ITS OWN

SPECIALISATION

• ALL THE CELLS IN AN ORGANISM HAVE THE COMPLETE GENOME

(GENETIC SEQUENCE)

• HOWEVER, WHEN CELLS DIFFERENTIATE (SPECIALISE), THEY ONLY

EXPRESS SOME OF THE GENES, AND MAY TURN OFF OTHERS

• THE DIFFERENT EXPRESS CAUSES THE VARIOUS TYPES OF CELLS

• THE CELLS CAN THEN FORM SPECIALISED TISSUES LIKE SKIN, THE

STOMACH, BRAIN OR LIVER

STEM CELLS

• STEM CELLS ARE UNDIFFERENTIATED CELLS

• THEY ARE CAPABLE OF BECOMING ANY TYPE OF CELL

• MAINLY FOUND IN EMBRYOS: THESE CELLS CAN BECOME ABSOLUTELY ANY

TYPE OF CELL

• ADULT STEM CELLS ARE MORE LIMITED AND CAN ONLY BECOME SELECT CELL

TYPES

THERAPEUTIC STEM CELLS

• STEM CELLS CAN BE USED FOR TISSUE REPAIR AND ORGAN REPLACEMENT

• THEY HAVE THE POTENTIAL TO CURE DISEASES AND REPAIR INJURIES (I.E. SPINAL INJURY,

CYSTIC FIBROSIS)

• HOWEVER, THERE IS CONTROVERSY, SINCE THE BEST STEM CELLS ARE

HARVESTED FROM EMBRYOS

• THERE HAS BEEN CULTURAL AND RELIGIOUS OBJECTIONS TO STEM

CELL RESEARCH

STEM CELL RESEARCH

• SCIENTISTS FROM ACROSS THE GLOBE HAVE WORKED TOGETHER ON STEM

CELL RESEARCH, WHICH MAKES THE RESEARCH GO FASTER

• THE WORK HOLDS GREAT PROMISE FOR THE TREATMENT OF DIABETES, HEART

DISEASE, AND MANY MORE

• BONE MARROW STEM CELLS ARE ALREADY USED FOR THERAPY