Living Environment Review

Breaking down and building up

Hydrolysis digestion: process of breaking large organic molecules such as proteins and starches into smaller molecules.Large molecules must be hydrolyzed before they

enter a cellSynthesis: building large organic molecules from small ones

Cells often use food molecules to build larger molecules they need

Dehydration Synthesis

What are the 4 classes of organic molecules?

1.Carbohydrates2.Lipids3.Proteins4.Nucleic Acids

Carbohydrates

• Monosaccharide = simple sugar– Examples include glucose, fructose, and ribose.

• Disaccharide = double sugar– Examples include sucrose, lactose, and maltose.

• Polysaccharide = complex sugar– Examples include storage polysaccharides such as

starch and glycogen, and structural polysaccharides such as cellulose and chitin.

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Lipids

• Fats and oils• Many different types• Are insoluble in water• Used for– Energy storage–Cell membranes– Steroid hormones–other

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Proteins• Large molecules—Long folded chains• Made up of many different combinations of 20

different types of amino acids• Differences in # & arrangement of amino acids

causes proteins to bend into different shapes. • The shape of the protein determines the

proteins function

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Function of proteins1. Defense ex antibodies2. Structure ex muscle3. Enzymes ex amylase4. Transport ex hemoglobin5. etc

Nucleic Acids

• Long chains of molecules called nucleotides• 2 types– DNA (deoxyribonucleic acid)• Stores hereditary information

– RNA (ribonucleic acid)

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Viruses are exceptions to the cell theory, but they have some characteristics of living things. What is one of these characteristics?

1. They are made up of many specialized cells.2. They contain genetic material.3. They reproduce by mitosis.4. They contain chlorophyll.

Correct Answer Number: 2

Explanation: Although virus' contain genetic material, they can not reproduce without being inside of a host cell. Many scientists question if they can be considered living or not, as this is the only life function they are capable of performing.

Which formula represents an organic compound?

1. Mg(OH)22. NaCl3. C12H22O114. NH3

Correct Answer Number: 3

Explanation: Organic compounds have Carbon (C) and Hydrogen (H) and are part of, or produced by, or excreted by living organisms.

Which is an organic compound found in most cells?

1. glucose2. water3. sodium chloride4. oxygen gas

Correct Answer Number: 1

Explanation: Organic means that the molecule contains carbon bonded to hydrogen. Only glucose, whose molecular formula is C6H12O6, has this. Although most cells also have an abundant amount of water (H2O) it is inorganic, as is sodium chloride (NaCl) and oxygen gas (O2).

Which are the four most abundant elements in living cells?

1. carbon, oxygen, nitrogen, sulfur2. carbon, oxygen, hydrogen, nitrogen3. carbon, oxygen, sulfur, phosphorus4. carbon, sulfur, hydrogen, magnesium

Correct Answer Number: 2

Explanation: Although all of these elements are found in living cells, the most abundant are carbon, hydrogen and oxygen (for carbohydrates and lipids) and nitrogen (for proteins and nucleic acids).

Which pair of compounds can be classified as inorganic?

1. nucleic acids and minerals2. proteins and water3. water and salts4. nucleic acids and proteins

Correct Answer Number: 3

Explanation: Organic compounds contain carbon and hydrogen bonds. Both nucleic acids and proteins contain these. Water (H2O) and salts (ex: NaCl) do not.

Nucleotides

Units that make up DNA molecule

Made of three parts1. 5 carbon sugar (deoxyribose)2. Phosphate group3. Nitrogen bases

4 kinds of nitrogen bases1. Adenine (A)2. Guanine (G)3. Cytosine (C)4. Thymine (T)

Chargaff’s Rule• A=T and G=C

X-Ray Evidence• Rosalind Franklin• British Scientist• Used a technique called

X-Ray diffraction • Provided important

clues about the structure of DNA

Watson & Crick

Prokaryotic Cells• Prokaryotic cells have a single circular

DNA molecule that contains nearly all of its genetic information

• Located in the cytoplasm

Eukaryotic Cells• Much more complex• 1000 times the amount of DNA as

prokaryotes• DNA is located in the nucleus in the

form of chromosomes

DNA coils around histones to form nucleosomes, which coil to form chromatin fibers. The chromatin fibers super coil to form chromosomes that are visible in the metaphase stage of mitosis.

Semiconservative Replication• Parental strands of DNA separate, serve as

templates, and produce DNA molecules that have one strand of parental DNA and one strand of new DNA.

Types of RNA1. Messanger RNA (mRNA)• Serve as messangers from DNA to the

rest of the cell2. Ribosomal RNA (rRNA)• Type of RNA that makes up parts of

ribosomes3. Transfer RNA (tRNA)• Transfers each amino acid to the

ribosome as it is specified by the mRNA

Transcription• RNA molecules are produced by copying part

of the DNA sequence into RNA• Transcription requires an enzyme known as

RNA polymerase• During transcription, RNA polymerase binds to

DNA and separates the DNA strands. RNA polymerase then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA.