Gene Structure and Genome Organization

Question 1

The self-replicating genetic structures of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes.

Answer 1

Chromosomes

Question 2

Three important DNA sequences

Answer 2

telomere, replication origin, and centromere

Question 3

The position at which the DNA helix is first opened and has binding sites for the initiator proteins and DNA regions that are especially easy to open.

Answer 3

Replication origin

Question 4

Sequences that serve as attachment for kinetochore that link chromosomes to mitotic spindles. Ensures equal distribution of chromosomes to daughter cells when a cell divides.

Answer 4

Centromere

Question 5

Sequences at the ends of eukaryotic chromosomes that help stabilize the chromosomes. Enable the ends of chromosomes to be efficiently replicated.

Answer 5

Telomere

Question 6

General telomere motif

Answer 6

(TxGy)n where x and y = 1 to 4

n = 20-100 in single celled eukaryotes; 1, 500 in mammals

Question 7

A gene is a portion of a chromosome that determines or affects a single character or phenotype.

Answer 7

Classic definition

Question 8

The classic definition of gene is based what precedences?

Answer 8

Laws of inheritance (Gregor Mendel) and Chromosome Theory of Inheritances (Thomas Hunt Morgan)

Question 9

“Particles” that determine traits occur in pairs and are separated into gametes during meiosis

Answer 9

Principle of segragation

Question 10

Alleles at one locus segregate into gametes independently of alleles at other loci.

Answer 10

Principle of independent assortment (no gene linkage)

Question 11

Explain the beadle and tatum experiment?

Answer 11

When spores were
exposed to mutagenic agents, mutants lacked one or another specific enzyme

Question 12

A gene is a segment of genetic material that determines or codes for one enzyme (one gene-one enzyme hypothesis).

Answer 12

Beadle and tatum molecular definition

Question 13

The beadle and tatum experiment involves an prototropic organism called?

Answer 13

Neurospora crassa

Question 14

What is the underlying reason for the development of one gene-one polypeptide definition of a gene?

Answer 14

Many genes code for proteins that are not enzymes

There are genes that code for a polypeptide of a multi-subunit protein

Question 15

Variant forms (alleles) of genes that occur in > 1% of the population

Answer 15

polymorphisms

Question 16

A gene is all the DNA that encodes the primary sequence of some final gene product which can either be a polypeptide or an RNA with a structural or catalytic function.

Answer 16

current definition, syn. smallest unit of heredity, a transcriptional unit

Question 17

Different forms of a gene at the same locus on homologous chromosomes

Answer 17

Allele

Question 18

Where does polymorphism come from?

Answer 18

inaccuracy during DNA replication

Question 19

Includes all the genes which carry the information for making the proteins required by the organism.

Answer 19

Genome

Question 20

General trend in the organism’s level of tropism and number of genes?

Answer 20

the lower the organism is, the higher the number of protein coding genes

Question 21

Non living characteristics of viruses

Answer 21

acellular
do not grow (only in number but not size) and divide
Outside the cell they possess DNA or RNA but never both

Question 22

Living characteristics of viruses

Answer 22

reproduce but only within living host

mutate

Question 23

An intact infectious viral particle is called a

Answer 23

virion

Question 24

Virion is composed of

Answer 24

capsid
nucleic acid
envelope (for some)