Genetics - FINAL - Unit 1

Describe the three ways that DNA structure fulfills the requirements of a hereditary molecule

1. Replication

2. Information content

3. Ability to change

List the atoms that make up DNA

P, O, C, H, N

Draw the detailed chemical structure of a generic deoxyribonucleotide (base not specified)

Describe the double-stranded nature of DNA, including base-pairing

• 2 anti-parallel strands

• base pairing rules A w/ T, G w/ C

List the four DNA deoxyribonucleotides, categorize them as a purine or pyrimidine

Purines

• Adenine & Guanine

Pyrimidines

• Cytosine & Thymine

Where does the base attach to the sugar?

At its 1’ carbon atom

Draw a short stretch of a DNA molecule, labeling hydrogen and covalent bonds, 5' and 3' ends, and the three components of each deoxyribonucleotide

Explain how the structure of DNA allows it to be faithfully replicated

One strand acts as a template strand

Describe the key elements of DNA & RNA function

• Complementary base pairing

• Recognition of specific sequences by proteins

Explain the relationship between DNA and chromosomes

DNA is the genetic material

chromosomes are tightly packed bundles of DNA that help it fit in the cell.

Distinguish between replicated and non-replicated chromosomes

Un-replicated Chromosome looks like I

Replicated chromosomes look like X

Describe the visible morphology and landmarks of a nuclear chromosome

two sister chromatids

a centromere that joins sister chromatids

telomeres at each end

Identify and draw chromosomes in various states (replicated/non-replicated, condensed/uncondensed)

Describe the relationship between homologous and non-homologous chromosomes

Homologous:

• Same genes, same shape

Non-homologous:

• Different genes, sometimes different shape

How does an individual acquire each member of a homologous pair or chromosomes?

Each member of the pair is obtained from mom and dad

Explain the concept of ploidy and different ploidy levels

Haploid: 1 set of chromosomes

Diploid: 2 sets of chromosomes

Polyploid: > 2 sets of chromosomes

Chromosomes

Packaged DNA

Centromere

Constricted region of a condensed chromosome

Kinetochore

Proteins that can bind the centromere sequence

Telomere

Unique DNA sequence at the ends of chromosomes, which proteins bind to

Homologous

Same genes, same shape

Non-homologous

Different genes, maybe different shape

Autosomes

Non-sex chromosomes

Sex chromosomes

X and Y in humans, chromosomes that look different between the sexes

Locus

Location on a chromsome

Allele

A version of a stretch of DNA that is mostly the same (DNA sequence)

Genotype

Combination of alleles

Homozygous

2 of the same (Ex: A/A)

Heterozygous

2 different (Ex: A/a)

Ploidy

Chromosome number

Haploid

1 set of chromosomes

Diploid

More than 1 set of chromosomes

Polyploid

More than 2 sets of chromosomes

Explain the origin of sister chromatids 

Sister chromatids are created when a chromosome is copied

What created chromatids?

DNA replication