Cellular Metabolism

Chapter 4

Introduction

Metabolism is many chemical reactionss Metabolism breaks down nutrients and

releases energy= catabolism Metabolism builds molecules to store

energy= anabolism

Anabolism

Eg. Dehydration synthesis

Anabolism

Peptide bonds link amino acids

Catabolism

Breaking larger molecules into smaller ones Eg: hydrolysis

Enzymes regulate all chemical reactions in cells

When a product is made Which product is made How much product is made How quickly the product is made

Enzyme Characteristics

Catalysts Reactions occur 1,000,000 times faster with

enzymes Not part of reaction

Not changed or affected by reaction Used over and over

Made of protein End in “-ase”

Enzyme and Substrate

DNA (Deoxyribonucleic acid)

Blue prints of enzymes Blueprints of proteins Deciphering genes, chromosomes, DNA.

How do they relate?

DNA

Genetic code This code instructs cells how to synthesize

enzymes and protein molecules. Portion of DNA with information for

making a particular protein is a GENE All of the DNA in a cell makes up the

genome

Human Genome

2% of the human genome encodes protein Rest controls when and where genes are

used Also many repetitive DNA sequences- we

don’t know what for. Completed in 2003

DNA replication

During cell division, DNA must be copied New cell receives a copy of the DNA

Bonds between base pairs of the double strands break

Review of Nucleic Acids

Contain C, H, O, N, P Function: energy carriers

ATP Function: genetic systems

DNA, RNA Determine what

proteins are made Structure: nucleotides

bonded together to form long chains

Nitrogen bases

RNA – 4 possible Adenine - A Cytosine - C Guanine - G Uracil – U

DNA – 4 possible Adenine – A Cytosine – C Guanine – G Thymine - T

Base Pairs

Nitrogen bases of the nucleotides occur in pairs Hold the 2 strands of DNA together

4 nitrogen bases in DNA Bonding is specific

A – T T – A C – G G – C

Sequence determines the order of amino acids in a protein

DNA Replication

DNA separates Each chain links itself to

DNA nitrogen bases Forms two new strands

of DNA

Protein Synthesis

HOW TO MAKE A PROTEIN? Need to find the correct order of amino

acids to build a protein.

Protein Synthesis - Transcription

DNA separates Each chain links itself to

RNA nitrogen bases (Transcription)

4 nitrogen bases in RNA Bonding is specific

A – U U – A C – G G – C

Forms a single strand of RNA

mRNA tRNA

Mutations may occur

RNA

Messenger RNA- carries the genes’ message out of the nucleus

Transfer RNA- correctly aligns amino acids to form proteins

Protein Synthesis - Translation

RNA “translates” genes’ messages

RNA moves out into cytoplasm mRNA binds to a

ribosome tRNA binds to specific

amino acids Carries them to mRNA

Amino acids bond together Form a protein

Summary of Replication, Transcription, Translation

Metabolism in Cells requires

Energy - ATP Aerobic respiration uses oxygen

Glucose enters cells Broken into smaller sugar molecules Occurs in cytoplasm

Yields 2 ATP These smaller sugar molecules are further metabolized

Enter mitochondria Series of chemical reactions yields 34 ATP

Aerobic Respiration

Metabolism in Body Cells (cont’d)

Anaerobic respiration occurs when oxygen is not present

Glucose enters cells Broken into smaller sugar molecules in cytoplasm

Yields 2 ATP

Fats and proteins are also used to make ATP