Download Getting to Know: The Function of Life

Getting to Know: The Function of Life
Why is it important to learn about cells? Cells are the primary building blocks of life. We can learn much about living things by studying how cells and their parts function. As you explore this concept, you’ll learn more about the way cells work and why they are important to living things.
What are the functions of cells?
Cells are the smallest unit of life. Some organisms are made of just one cell, while other organisms are made of millions of cells. Cells enable many life processes, including movement, thought, digestion, and excretion of waste or fluids. Additionally, cells perform protein synthesis, which means they can produce proteins needed to support the cell or to reproduce genetic material. Protein synthesis enables organisms to grow and reproduce. Growth and reproduction are directly related to the larger organism. If cells were not able to grow or reproduce, we would never be able to grow from an embryo into a baby, then into adulthood.
Cells are also responsible for two other processes:
Learning about the function of cells
respiration and regulation. Cellular respiration is the
can help you learn more about plants
process that changes chemical energy into energy
and animals.
for life. Plants perform cellular respiration as they
convert glucose (sugar) into energy. In animal cells,
respiration occurs when the cells break down carbohydrates. Cellular regulation is the process
by which cells maintain homeostasis. Homeostasis is the tendency of a cell to maintain the
conditions necessary for survival. For example homeostasis helps a cell maintain a stable
temperature and the proper amount of water. Homeostasis helps an organism stay healthy
and alive.
Misconception: We just started learning about cells in science class. Do all cells
have a cell wall?
Not every cell type has a cell wall. All cells do have a cell membrane, which helps control
which substances move in and out of the cell, but only plant cells have a cell wall.
Concept: The Function of Life
Getting to Know
www.discoveryeducation.com
1
© Discovery Education. All rights reserved.
Discovery Education is a subsidiary
of Discovery Communications, LLC.
Do the parts of cells have specific functions?
Organelles are tiny structures within the cell. All organelles, whether they are within a plant cell or an animal cell, have specific functions. Let’s quickly review a few organelles and their functions. You’ll learn more about them as you study this concept.
Cytoplasm is a thick liquid that holds all of the
organelles; its function is to protect and contain
the organelles. The nucleus is the cell control center.
It contains the genetic material of a cell, which
helps determine the functions and traits of the
larger organism. The cell membrane regulates how
materials enter and exit the cell. It helps hold all
of the organelles inside of the cell, and also allows
fluids to enter or exit the cell.
The mitochondria are tiny organelles that act as
centers for cellular respiration. They’re responsible
for converting chemical energy into usable energy
for life, and they release that energy for the cell to
use. Ribosomes are also tiny organelles. Ribosomes
help with protein synthesis and other biochemical
processes. Vacuoles are structures that are filled
with air, water, food, or waste products. In an
animal cell, the cell vacuoles are called lysosomes.
Are plant cells identical to animal cells?
Unlike animal cells, plant cells have cell
walls and chloroplasts.
Plant cells have additional organelles. For example,
plant cells are surrounded by a cell wall, which
helps keep the cell rigid and supports the plant.
They also have chloroplasts, which are the sites
where photosynthesis occurs.
As you learn about cells, think about how cell structure and function are related. Is every cell
in your body identical, or are there different types of cells?
Concept: The Function of Life
Getting to Know
www.discoveryeducation.com
2
© Discovery Education. All rights reserved.
Discovery Education is a subsidiary
of Discovery Communications, LLC.