BIOL 3303 Genetics -- Dr. Pfau Exam 1

What Contains most of the cell's genetic material in the form of linear strands of DNA (chromosomes)?

Nucleus

What is fused to nuclear membrane; site of protein synthesis, packaging, and transport?

Endoplasmic reticulum

What do we call the structures in a cell on which translation occurs?

Ribosomes

What is a stack of membranes where proteins are packaged for transport to other parts of the cell?

Golgi body (or Golgi apparatus)

What is the name of a sac used for storing or holding substances within the cell?

Vacuole

Where is the primary site of ATP production (ATP is the energy source of cellular reactions)?

Mitochondria

What contains chlorophyll; site of photosynthesis?

Chloroplast (or plastid)

What contains enzymes for intracellular digestion?

Lysozome

What is the area/structure where microtubules (spindle fibers) form during cell division?

Centriole (or centrosome)

What is the name of the extensions of the cell typically used for movement?

Cilia/flagella

What are the three ways that DNA structure fulfills the requirements of a hereditary molecule?

1. Replication

2. Information Content

3. Ability to change

What are the atoms that make up DNA?

1. Hydrogen

2. Oxygen

3. Carbon

4. Nitrogen

5. Phosphorus

What is the double-stranded nature of DNA?

1. Complementary - G/C (3 hydrogen bonds) and A/T (2 hydrogen bonds)

2. Antiparallel - 3'/5'

What is the base-pairing rule?

Purines pair only with pyrimidines due to base attraction of charges.

G w/ C and A w/ T

What DNA deoxyribonucleotides are a purine?

G - Guanine

A - Adenine

What DNA deoxyribonucleotides are a pyrimidine?

C - Cytosine

T - Thymine

How does the structure of DNA allow it to be faithfully replicated?

Each single strand forms a template

Describe the double helix

- it has major and minor grooves

-mechanism: attraction is due to molecular force along the length which causes a single strand to pair with a complementary single strand.

What are the two key elements of DNA and RNA function?

1. Complementary base pairings

2. Recongnition of specific sequences by proteins

What are the 3 components of a Deoxyribonucleotide?

1. Phosphate group

2. deoxyribose sugar

3. nitrogenous base

what are the two definitions for Gene?

1. a specific stretch of DNA that contains the information to produce a RNA molecule, which may or may not be used to produce a polypeptide, which may or may not by itself be a protein.

2. a unit of transcription

What are products of gene expression?

- polypeptides (protein) or RNA (mRNA, tRNA, rRNA)

What are the different functions of proteins?

1. Enzymes

2. Immunoglobulins

3. Hormones

4. Receptor proteins

5. Membrane gateways/channels

6. carrier proteins

7. structrual proteins

8. DNA/RNA binding proteins

9. Ribosmal protiens

10. Contractile proteins

What are the 3 functional regions of a gene?

1. Promoter: forms the beginning of a gene

2. Transcribed region

3. Termination sequence: ends the gene

What does a Eukaryotic gene have that a prokaryotic gene does not?

Intron- the filler in genes which is needed to separate Exons that carry information, otherwise their genes wouldn't express like those in the prokaryotic genes.

How is a chromosome packaged?

starts as a Nucleosomes (an 11 nm wide fiber) then becomes a 30 nm wide fiber as it compresses then after additional looping and coiling becomes a protein and then loops and coils again to become a whole chromosome.

What is the difference between a heterochromatin and a euchromatin?

heterochromatin is a more compact portion of chromatin and euchromatin is less intense/compact.

How are sister chromatids created?

by DNA replication

What is the morphology of a nuclear chromosome?

1. Start with an unreplicated chromosome (uncondensed, 1x dsDNA)

2. DNA Replication occurs leaving a replicated chromosome (uncondensed, 2x dsDNA = sister chromatid)

3. Condensation occurs leaving a replicated chromosome (condensed, 2x dsDNA)

4. Separation occurs leaving 2 unreplicated chromosomes (condensed, 1x dsDNA each)

5. Uncondensing occurs leaving 2 unreplicated chromosomes (uncondensed, 1x dsDNA each)

6. Cell divides leaving one unreplicated chromosome in both new cells (uncondensed, 1x dsDNA each)

Cycle starts over

What is a centromere?

The location where kinetochore attaches. It has a unique DNA sequence.

What is a kinetochore?

a molecular motor that pulls a chromosome across the spindle fiber

What is a telomere?

The ends of chromosomes. Also has a unique DNA sequence.

What is a karyotype?

a diagram made by people to help visualize the pairing of chromosomes from a chromosome spread.

What are homologous chromosomes?

chromosomes with the same genes, size and shape

Define sex chromosomes

the chromosomes that are different in the heterogametic sex (X&Y = male in humans)

What type of sex chromosomes are in birds and what is different about them from humans?

Z&W -- female birds are the heterogametic sex

Where do homologous pair of chromosomes come from?

one from the mother and one from the father

What is the definition of an Allele?

a version of a DNA sequence at a particular locus

What creates different alleles?

mutations in the DNA sequence

What is an Indel?

An insertion or deletion in an Allele DNA sequence

What is a genotype?

a combination of alleles that an individual has.

Define locus (plo loci)

location

What are the two aspects of ploidy (chromosome number)?

-How many sets of chromosomes?

- How many chromosomes are in a set?

What is the condition of having only one set of chromosomes?

haploid

What is the condition of have two sets of chromosomes?

diploid

What is the condition of having 3 or more sets of chromosomes?

polyloid

How have chromosomes evolved over time?

some chromosomes have fused together over time in some breeds of species to create new breeds

Ex: Great Apes v. Human and Reeve's Muntjae v. Indian Muntjae

What is a genome?

All of the DNA in a cell or organelle/organism

How do genomes vary from species to species?

1. amount of DNA

2. format of DNA (linear v. circular and the type of packaging)

3. number of chromosomes

4. organization of DNA (some mammals have the same genes but in a different order)

What are the three different types of DNA sequences?

1. genes (10%)

2. regulatory sequences (10%)

3. Non functional sequences (80% of DNA sequences)

What are regulatory sequences used for?

to regulate the expression of genes

What are the 4 types of non-functional DNA sequences?

1. pseudogenes (remnants of genes that used to function in our ancestors)

2. repetitive sequences (ex: GAGAGA -- used for DNA tests)

3. viral sequences (DNA viruses that had infected our ancestors)

4. transposable elements (DNA sequences that can copy and paste themselves within the genome --most common genome)

Describe a prokaryotic genome.

-most are single stranded, circular DNA

- 100,000 - 10 mil bp

- few if any introns

What are the two different types of Eukaryotic genomes?

1. nuclear

2. organelles

What features describe a nuclear genome?

- linear, dsDNA

- 2 million - 680 billion bp

- have many introns

What features describe an organelles genome?

- typically circular

- 5,000 - 200,000 bp

- genes control organelle function

What is endosymbiosis?

it explains where mitochondria and plastids come from.

What features describe a viral genome?

- can be single or double stranded

-circular or linear

-can be DNA or RNA (this is special about this genome)

-150,000 - 300,000 bp