86 Chapter 4
Career
Focus
As the Body Ages
As we age, our metabolism slows down considerably because we do not need as
much energy for growth and maintenance as we did in our youth. Hence, we do
not need the same caloric intake as we did in the past. We should reduce the
amount of food we take in daily to prevent the “inevitable” weight gains we expe-
rience from our early 40s onward. Daily exercise also helps -reduce this weight
gain.
Women stop ovulating and producing eggs by meiosis after menopause.
However, men continue to produce sperm cells well into their 80s. It is there-fore
not uncommon for a male to father a child when in his 70s.These are careers that are available to individuals interested in metabolism:^
Nutritionists have completed advanced degrees in foods and nutrition and work as
professionals in hospitals, childcare centers, school systems, and nursing homes.^
● Dieticians establish daily balanced dietary intakes of fluids and foods for people from
early childhood through old age.^
There are also careers for individuals interested in cellular reproduction.^
● Genetic engineers work with recombinant DNA to study altering and controlling the
phenotype (appearance) and genotype (genes) of organisms. In the future, this work
may offer the possibility of eliminating or controlling genetic disorders in humans.^
● Gerontologists study the aging process and its sociological, economic, psycholog-
ical, and clinical effects experienced by the elderly.^
● Consultants in planned parenthood assist in family planning programs, providing
information on how to become pregnant or how to prevent an unwanted pregnancy.Summary Outline
Introduction to Cellular
Metabolism
- The most common form of chemical energy that
maintains cellular structure and function is the
molecule- ATP (adenosine triphosphate).^
- Metabolism is a general term that describes the total
chemical changes that occur in cells. There are two
subcategories: anabolism is the energy-requiring
process that builds larger molecules by combining
smaller molecules, and catabolism is the energy-
releasing process that breaks down larger mol-ecules
into smaller ones. These cellular metabolic processes-
are often called cellular respiration.
3. ATP is made in a stepwise catabolism (decomposi-
tion) of food molecules like glucose. The chemical^
energy in food (calories) is released and used to put
together ADP (adenosine diphosphate) and PO 4
(phosphate) to make ATP.^ - The overall chemical equation for cellular res-
piration is: C 6 H 12 O 6 1 6O 2 S 6CO 2 1 6H 2 O 1 38
ATP or 36 ATP and 2 GTP.^ - Cellular respiration consists of three processes or steps:
glycolysis, Krebs citric acid cycle, and electron transport.
Glycolysis- Glycolysis occurs in the cytoplasm of the cell and
does not require oxygen.^ - We must use two ATP molecules to start glycolysis and
these must be “paid back” from our production of ATP.