Cell metabolism

1. Cell Metabolism

2. Cell Respiration (Metabolism)
•Cellular Respiration- is a metabolic process
used to obtain energy from organic compounds
or food
•can run under aerobic and anaerobic
conditions.
•catabolic pathway.
•occurs in the cytoplasm and mitochondria
•3 main steps: Glycolysis and the Kreb Cycle,
also known as the citric acid cycle and
tricarboxylic acid cycle, and the ETC (electron
transport chain)

3. Cellular Metabolism
Metabolism – all chemical reactions that
occur in the body
Two types of metabolic reactions
Anabolic Catabolic

4. Goal of Cell Respiration-Make ATP

5. Anabolic
Anabolism provides the substances needed for
cellular growth and repair
Dehydration synthesis
●
type of anabolic process
●
used to make polysaccharides, triglycerides, and
proteins- produces water

7. Catabolic
Catabolism breaks down larger molecules into smaller ones
Hydrolysis
●
used to decompose carbohydrates, lipids, and proteins
●
water is used
●
reverse of dehydration synthesis

8. Control of Metabolic
Reactions
Enzymes- all are proteins
lower activation energy
•not consumed in
chemical reactions
•substrate specific
•Controlled through
feedback inhibition

9. Do not make
anything happen that
could not happen on
its own
Enzymes can be
reused over and over
Same enzymes
catalyses the forward
and reverse reactions.
They are very
specific

12. Control of Metabolic Reactions
Metabolic pathways
●
series of enzyme-controlled reactions leading to
formation of a product
●

Enzyme names commonly
●
reflect the substrate
●
have the suffix – ase
●
sucrase, lactase, protease, lipase

13. Control of Metabolic Reactions
Cofactors
●
make some enzymes
active
●
ions or coenzymes
Coenzymes
●
organic molecules
that act as cofactors
●
vitamins
Factors that alter enzymes
●
heat
●
radiation
●
electricity
●
chemicals
●
changes in pH

14. Energy for Metabolic
Reactions
Energy
●
ability to do work or change something
●
heat, light, sound, electricity, mechanical energy,
chemical energy
●
involved in all metabolic reactions

15. Cellular Respiration
Occurs in three series of reactions
●
Glycolysis
●
Citric acid cycle
●
Electron transport chain
Produces
●
carbon dioxide
●
water
●
ATP (chemical energy)
●
heat
Includes
● anaerobic reactions (without O
2
) - produce little ATP
● aerobic reactions (requires O
2
) - produce most ATP

17. Glycolysis
•There are 10 steps
and all require
specific enzymes to
catalyze them
•Goal- Produce
pyruvate for use in
the Krebs Cycle
•NADH used in ETC

18. Citric Acid Cycle
• begins when acetyl CoA combines with oxaloacetic acid to
produce citric acid
• citric acid is changed into oxaloacetic acid through a series of
reactions
• cycle repeats as long as pyruvic acid and oxygen are available
•Makes 2 ATP 6 NADH and 2 FADH2
•BP- 4 CO2

19. The Goal is the
production of NADH
and FADH2 for use
in the ETC—they are
electron carriers

20. ETC
•So far only 4 of the 38 ATP that will be produced have
been, all by substrate level phosphorylation.
•The remaining will be produced by the ETC.
•The majority of the ATP produced comes from the
energy carried in the electrons of NADH (and FADH
2
)
that were produced by the Krebs Cycle. 6 NADH and
2 FADH
2
•The energy in these electrons is used in the ETC to
power the synthesis of ATP.
•There are thousands of ETC’s found in each
mitochondria, which can number in the 100’s
depending on the cell type.

21. Oxygen if the Final Electron Acceptor
Why do we Breath??

23. Summary of
Catabolism of
Proteins,
Carbohydrates,
and Fats
4-21

24. Carbohydrate Storage
Excess glucose stored as
●
glycogen (primarily by liver and muscle cells)
●
fat
●
converted to amino acids

25. Regulation of
Metabolic
Pathways
Turned off when
their product is in
strong supply
Works by supply and
demand
4-23

26. Nucleic Acids and
Protein Synthesis
Gene – segment of DNA that codes for one protein
Genome – complete set of genes

27. The Central Dogma
•It is all about Proteins!!!
•DNA contains the information needed to build
these life giving proteins in a code on segments
called genes.
•One gene can code for more than one protein?

28. Structure of DNA
• two polynucleotide chains
●
hydrogen bonds hold
nitrogenous bases
together
●
bases pair specifically
(A-T and C-G)
●
forms a helix
●
DNA wrapped about
histones forms
chromosomes

30. RNA Molecules
mRNA
rRNA
tRNA

31. Protein Synthesis (Transcription
and Translation)
•1st the DNA strand is used as a template to
build a molecule of RNA called mRNA that
can leave the nucleus taking the instructions
for the protein to ribosome for assembly.
•2
nd
during translation the information
contained in the RNA molecule is used to
determine the sequence of amino acids
needed to build a protein.
•Order: DNA - RNA – protein - trait.

34. Translation

35. Overview:
Protein
Synthesis

36. DNA Replication

37. Mutations
Mutations – change in genetic
information
Result when
●
extra bases are added or
deleted
●
bases are changed
May or may not change the
protein
Some good some bad

38. Clinical Application
Phenylketonuria
PKU
• enzyme that breaks down the amino acid
phenylalanine is missing
• build up of phenylalanine causes mental
retardation
• treated by diets very low in phenylalanine