Ch 2.3 Plant and Animal Cellular Processes

Cellular Processes

• whether we are asleep or awake, active or lounging on the couch, our cells are constantly working, transporting raw materials, converting energy and transporting energy, building proteins, and sending chemical messages

Transforming Energy• all cellular activities need energy• mitochondria provide energy to the cell by

transforming oxygen and sugar into carbon dioxide and water in a process called cellular respiration

• cellular respiration occurs in both plant and animal cells

• in plant cells, chloroplasts in the cells produce the sugar needed by the mitochondria in a process called photosynthesis

Processing and Transporting Materials

water, gases, and nutrients enter the cells through the cell membrane

materials move through the cytoplasm to the various organelles

the endoplasmic reticulum makes proteins from raw materials that come through the cell and passes them to the Golgi apparatus

the Golgi apparatus processes protein molecules and secretes them outside the cell to be used elsewhere in the organism

lysosomes break down food and digest wastes

All of this cellular activity is controlled by the nucleus!

Reproducing• cells have a lifespan– amoebas live for ~2 days– human brain cells ~30-50 years– human red blood cells ~120 days– human skin cells ~20 days

• cells die because– they have been damaged– they have not received enough water or food– they have reached the end of their lifespan

ROUGHLY 3 BILLION

CELLS IN OUR BODIES

DIE EVERY DAY!!

With all these cells dying every day, wouldn’t you expect multicellular organisms to shrink over time?

Reproducing

• before the cell dies, it splits (through cell division) to create a replacement for itself

• in animal cells, the nucleus first splits in two; then the membrane pinches near the middle to divide the cytoplasm, along with all its organelles, and ensures that each new cell has a nucleus

• the two new cells are identical

Animal Cell Division

Reproducing

• bin plant cells, instead of the cell membrane pinching the cell in two after the nucleus splits, a new cell plate develops across the cell to create a new cell wall between the two nuclei

Plant Cell Division