Genetics Chapter 1

What is Chapter 1 called?

Genetics: From Genes to Genomes.

What is genetics

The study of biological information

What is the Chapter 1 course framework for studying genetics?

God created the heavens and earth, sustains the created order, and creation reveals God to everyone.

What does “general revelation” refer to in the Chapter 1 notes?

Everything God has done and created has been revealed to everyone.

What does the “D” in DNA stand for?

Deoxyribose.

What three things make up a DNA nucleotide?

A phosphate group, deoxyribose sugar, and nitrogenous base.

What four nitrogenous bases are in DNA?

Adenine, cytosine, guanine, and thymine.

What is DNA?

A polymer of nucleotide subunits.

What is a nucleoside compared with a nucleotide?

A nucleoside is a base plus sugar; a nucleotide is base plus sugar plus phosphate.

What are complementary DNA base pairs?

A–T and G–C.

How many hydrogen bonds are in A–T and G–C pairs?

A–T has two; G–C has three.

What does it mean that DNA strands are complementary and oppositely oriented?

Their bases pair specifically, and one strand runs 5′→3′ while the other runs 3′→5′.

What encodes biological information in DNA?

The nucleotide sequence—the ordering of A, C, G, and T.

Why are DNA’s two complementary strands important?

They provide a mechanism for copying and maintaining biological information.

Put nucleotide, gene, and chromosome in order of increasing complexity.

Nucleotide → gene → chromosome.

What is a gene in Chapter 1?

A sequence of DNA that encodes a protein.

What is a chromosome?

DNA molecules and proteins assembled into a chromosome; each chromosome contains many genes.

What is a genome?

The entire collection of chromosomes in each cell of an organism.

How many chromosomes are in the human genome?

46.

How are chromosomes arranged in females and males?

Females have 23 sets of two; males have 22 sets of two plus X and Y.

How many base pairs are in the human genome?

About 3 × 10⁹ base pairs.

How many human genes does the slide estimate?

About 20,000–30,000.

What are proteins made of?

Hundreds to thousands of amino acids.

How many different amino acids are there?

20.

What determines a protein’s amino-acid sequence?

The ordering of information in DNA.

What determines protein type, three-dimensional structure, and function?

The order of amino acids.

How many bases are in one codon, and how many possible codons are there?

Three bases; 4³ = 64 possible combinations.

What three parts make up an amino acid?

An amino group, carboxyl group, and side chain.

What determines an amino acid’s chemical properties?

Its side chain.

How is a peptide bond formed?

The carboxyl group of one amino acid reacts with the amino group of another and releases water.

What is a polypeptide?

Many amino acids joined by peptide bonds; it can be part or all of a protein.

What does a different amino-acid sequence cause?

A different three-dimensional protein shape and different function.

Match protein roles to examples.

Antibody—IgG; enzyme—phenylalanine hydroxylase; messenger—growth hormone; structural—actin; transport/storage—ferritin.

How does RNA differ from DNA in sugar and fourth base?

RNA has ribose and uracil; DNA has deoxyribose and thymine.

Why is RNA relatively unstable?

It is particularly unstable as single-stranded RNA.

What information-related abilities does RNA have?

It can store, replicate, mutate, and express information.

What protein-like abilities does RNA have?

It can fold in three dimensions and catalyze chemical processes.

What molecular specialization do all living organisms share?

DNA stores/replicates information; RNA is an intermediate in protein production; proteins catalyze processes.

How is the genetic code read?

Bases are read as triplets to encode amino-acid subunits of proteins.

What codons can code for phenylalanine in the notes?

UUU or UUC.

What is a silent mutation?

A nucleotide change that does not change the amino acid.

What can one nucleotide change sometimes do?

Change an amino acid entirely; sickle-cell anemia is an example.

What is the one-letter code for Ala, Arg, Asn, Asp, Cys?

A, R, N, D, C.

What is the one-letter code for Gln, Glu, Gly, His, Ile?

Q, E, G, H, I.

What is the one-letter code for Leu, Lys, Met, Phe, Pro?

L, K, M, F, P.

What is the one-letter code for Ser, Thr, Trp, Tyr, Val?

S, T, W, Y, V.

What does cytochrome C comparison among species show?

Genes with similar functions in different organisms often have similar gene products.

What does Pax6 demonstrate?

A gene from one organism can often functionally replace a gene in another; human Pax6 can induce eye development in Drosophila.

What is the proposed source of gene families?

Duplication of ancestral genes followed by sequence divergence.

What three things do regulatory networks affect?

Location, timing, and level of gene expression.

What fly change was made by changing a regulatory-network element?

A two-winged fly was changed to a four-winged fly by converting halteres to wings.

What is genetic dissection of a model organism?

Inactivate a gene, observe consequences, and infer the function of its gene product.

What is genomics?

Determining entire genome sequences, analyzing all genes at once, and identifying differences between individuals.

What did the original human genome project take and cost?

10 years and $3 billion.

What do advances reduce genome sequencing to according to the slide?

Days and a few hundred dollars.

Why are model organisms valuable?

They provide information about aspects of biology that are conserved.

What are helpful uses of genetic information?

Predict future possibilities and risks; design therapeutic drugs to prevent or minimize symptoms of gene-based disease.

What are harmful uses of genetic information?

Discrimination, restricting people’s lives, and misinterpretation of information.

What is the difference between disease genes described on the slide?

Some always cause disease; some predispose a person to disease.

Why is education in risk and probability essential?

For understanding and interpreting genetic information.

What law was passed in 2008?

The Genetic Information Nondiscrimination Act.

What is the final Chapter 1 principle?

Be wise—practice good stewardship.