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