cell reproduction. why do cells divide? to create new cells to replace dead cells to allow growth to...
TRANSCRIPT
CELL REPRODUCTION
WHY DO CELLS DIVIDE?
• TO CREATE NEW CELLS• TO REPLACE DEAD CELLS• TO ALLOW GROWTH• TO REPAIR DAMAGED OR
INJURED CELLS
WHY MUST CELLS BE SMALL?
• CELLS CAN ONLY METABOLIZE AS THEY RECEIVE MATERIALS• DIFFUSION IS SLOW AND
INEFFICIENT OVER LONG DISTANCES, SO CELLS MUST BE SMALL
• VOLUME INCREASES MUCH FASTER THAN SURFACE AREA• SMALL SURFACE AREA
CANNOT EFFICIENTLY TAKE IN OR REMOVE MATERIALS FROM A LARGE VOLUME.
CELL IS POISONED OR STARVES
2 TYPES OF REPRODUCTION
• ASEXUAL REPRODUCTION
• SEXUAL REPRODUCTION
ASEXUAL REPRODUCTION
• PRODUCING OFFSPRING FROM ONE PARENT• PRODUCE AN EXACT COPY OF
THE PARENT BECAUSE THE GENES ARE THE SAME
BINARY FISSION
• PRODUCTION OF 2 CELLS OF THE SAME SIZE.• EXAMPLES: BACTERIA, ALGAE
& PROTOZOA
SPORE FORMATION
• TINY ASEXUAL REPRODUCTIVE CELLS WITH A HARD OUTER WALL– DEVELOPS INTO A NEW ORGANISM• EX: FUNGUS
BUDDING
• A SMALL BUD GROWS DIRECTLY FROM THE BODY OF THE PARENT AND LATER SEPARATES.
• Brown hydra - Hydra oligactis - video 09.html - ARKive
VEGETATIVE PROPAGATION
• SMALL PLANTS FORM FROM ROOTS, STEMS, OR LEAVES OF OTHER PLANTS.• EXAMPLES: STRAWBERRIES,
POTATO & SPIDER PLANT
REGENERATION
• DEVELOPMENT OF A NEW ANIMAL FROM PART OF ANOTHER.• STARFISH & JELLYFISH
SEXUAL REPRODUCTION
• TWO PARENTS PRODUCE OFFSPRING• EACH CONTRIBUTES GENES
(TRAITS) TO THE OFFSPRING
GAMETES – SEX CELLS• FEMALE GAMETE + MALE GAMETE EGG CELL SPERMCHROMOSOME # 23 CHROMOSOME # 23
FERTILIZED EGG (ZYGOTE) CHROMOSOME # = 46
FERTILIZATION – IS THE PROCESS WHERE EGG & SPERM COMBINE TO FORM A ZYGOTE