Chapter 4

Question 1

What is the nucleus the site of?

Answer 1

DNA replication
RNA synthesis
RNA processing
Ribosome assembly

Question 2

What does the nuclear envelope or membrane contain?

Answer 2

Two phospholipid bilayers- outer membrane is continuous with endoplasmic reticulum, inner membrane has proteins that bind the nuclear lamina
Nuclear lamina (protein framework)- mesh that provides structural support, consists of fiborous proteins called lamins 
Nuclear pores

Slides 6-9

Question 3

What is genotype and phenotype?

Answer 3

Genotype- genetic composition of an organism (RR)

Phenotype- physical appearance of an organism (red trait)

Question 4

How does the number of linkage groups relate to the number of chromosomes?

Answer 4

Number of linkage groups=number of chromosomes

Phenotypic traits are inherited together as linkage groups

Question 5

What is replication, transcription, and translation in DNA synthesis?
Guaranteed test questions on this

Answer 5

Replication- duplicate copy of DNA molecule made by DNA polymerase
Transcription- synthesis of RNA molecule from a DNA template by RNA polymerase
RNA synthesis using DNA template
Nucleotide->nucleotide
Translation- synthesis of polypeptide chain from an mRNA template (ribosomes)
Protein synthesis using mRNA template
Nucleotide->amino acid

Question 6

What are mRNAs, rRNAs, and tRNAs?

Answer 6

mRNA- molecules that serve as templates for protein synthesis
rRNA- component of ribosomes
tRNA- adaptor molecules that align amino acids along the mRNA template

Question 7

What is the genetic code?

Answer 7

Corresponding information from nucleotide triplets called codons that encode individual amino acids in proteins
Codons are the basic units of the genetic code

Picture on slide 20

Question 8

What is a general TREND between organism complexity and genome size?

Answer 8

It often happens that increased genome complexity=increased genome size

Question 9

What is a gene?

Answer 9

A segment of DNA within a chromosome that is expressed to yield a functional product

Genes make up a small proportion of the entire genome

Slide 29

Question 10

What are exons, introns, and RNA splicing?

Answer 10

Exons are segments of protein-coding sequence
Introns are segments of nonprotein coding sequences, they make up the majority of a genes RNA coding region
RNA splicing is the joining of exons in a precursor mRNA molecule

Slide 24

Question 11

How does the size of eukaryotic organism affect the number of genes, protein coding sequence, intron sequence, and introns per gene?

Answer 11

If size goes up
Number of genes go up
Protein coding sequence percentage goes down
Intron sequence percentage goes up
Introns per gene go up

Question 12

What is the other 60-70% of the human genome that is not a typical gene?

Answer 12

Several types of highly repeating sequences that make up a significant portion of the remainder of the genome
Many of these have been found to encode regulatory RNAs that play important roles in regulation of other genes (micro RNAs and long non-coding RNA’s) or stability and replication of chromosomes

Question 13

What is the simplest present day prokaryote?

Answer 13

Mycoplasma genitalium
Second smallest genome of known cells
Minimal gene set required to maintain self replicating organism

Question 14

What is he major question about phenotypic complexity and genetic complexity?

Answer 14

How phenotypic complexity is generated since it does not rely solely on increased genetic complexity

Question 15

What is the human genome?

Answer 15

Distributed on 24 different chromosomes
22 autosomes, X and Y sex chromosomes
Human genome consists of approx 21000 genes and contain more intron sequence than genes in smaller animals

Question 16

What is chromatin?

Answer 16

Eukaryotic chromosomal DNA complexes with proteins

Typically about twice as much protein as DNA

Question 17

Is chromosome number related to complexity in the animal?

Answer 17

NO

Question 18

What are nucleosomes and histones?

Answer 18

Nucleosomes are the basic structural units of chromatin
They consist of DNA+histones
Chromatosome is 166 basepairs plus histone H1

Histones are small proteins containing high proportion of the basic amino acids arginine and lysine. This facilitated binding to the negatively charged DNA sugar phosphate backbone
H1, H2A, H2B, H3, H4

Slide 41-43

Question 19

What are euchromatin and heterochromatin?

Answer 19

Euchromatin- decondensed-transcriptionally active interphase chromatin
Heterochromatin- highly condensed, transcriptionally inactive chromatin, contains highly repeated DNA sequences (Arrowheads on TEM)

Slide 45

Question 20

What are the two types of heterochromatin?

Answer 20

Constitutive heterochromatin- contains DNA that is not transcribed in any cell type
DNA sequences at centromeres
Facultative heterochromatin- contains DNA sequences that are not transcribed in the cell being examined but may be transcribed in other cell types

Question 21

How is the DNA organized in metaphase chromosomes?

Answer 21

Organized into large loops attached to a protein scaffold

Question 22

What is a centromere and a kinetochore?

Answer 22

Centromere- region of chromosome that plays a critical role in editing the correct distribution of duplicated chromosomes to daughter cells during mitosis
Contains a histone known as centromeric histone H3
Kinetochore- a protein structure associated with the centromere where microtubules bind

Slide 49

Question 23

What are telomeres?

Answer 23

Sequences at the ends of eukaryotic chromosomes
Role in maintaining stability of linear chromosomes
Maintained by unique enzyme known as telomerase
Slide 53 structure