Genetics Midterm One

How many chromosomes does a prokaryote have?

1 chromosome

How do prokaryotic cells divide?

Binary Fission

What is a karyotype

A pairing and classification of chromosomes in an organism

Which side of the chromosome is the p arm

The shorter side

Which side of the chromosome is the q arm

The longer side

What is the name of the ends of the chromosome

Telomere

What is the name of the space between the q and p arm?

Centromere

What kind of chromosome is this

Metacentric

What kind of chromosome is this

Submetacentric

What kind of chromosome is this

Acrocentric

What kind of chromosome is this?

Telocentric

What is the value of n in humans?

23

What is a homologous chromsome?

A pair of chromosomes that code for the same gene with different nucleotide sequences

What does mitosis do?

Create perfect diploid cell copies

What is G1?

A checkpoint during interphase for cell growth and protein synthesis

What happens during the G1/S check?

Makes sure the cell is ready to divide, is it the right size, does it have nutrients, etc!

What goes on during the S phase

DNA Replication and centrosome duplication

What are sister chromatids held together with?

A protein called cohesin

How many DNA molecules in one sister chromatid?

One DNA molecule

What is the difference between sister chromatids and a homologous chromosome pair?

Sister chromatids are exact duplicate DNA sequences, Homologous chromosome pairs are pairs of chromosomes that code for the same gene but are not the same nucleotide sequence

Does the number of chromosomes change during S phase?

No

Does the number of DNA molecules change during the s phase?

Yes, they double

What goes on during G2?

Cell growth and protein synthesis

What goes on during the G2/M check?

To check and make sure the DNA is replicated and undamaged

What do microtubules do?

Connect centrosome to kinetochore on each chromatid

What happens during Prophase?

Mitotic spindles starts to form from centrosomes, chromsome begins to condense, nucleolous is gone

What happens during prometaphase

Nuclear envelope breaks down, chromosomes are now fully condensed

What happens during metaphase?

Chromosomes line up at the metaphase plate

What happens during anaphase?

Separase breaks down cohesin, and allows kinetochores to pull chromosomes toward poles. Microtubules also push poles apart, elongating the cell

What is the spindle assembly checkpoint?

A checkpoint that prevents anaphase until all chromosomes are in their correct spot (in line) to be properly separated

What happens during Telophase?

Chromosomes begin decondensing, spindle disappears, nuclear membrane re-forms, and nucleolus comes back

What happens during Cytokinesis?

Cell cleavage/splitting to create two identical daughter cells

What is endoreplication?

When there is an abnormally large nucleus (failure of mitosis and cytokinesis but successful DNA replication)

What is mosaicism

When someone has two or more genetically different sets of cells in their body

What is chromosomal nondisjunction

when chromosomes dont separate correctly during cell division

What is the purpose of meiosis?

Preperation for s3xual reproduction

What do prokarotic cells do instead of meiosis?

bacterial conjugation

What happens during Prophase 1

Homologous Chromosomes pair up and cross over (swap DNA)

What happens during Metaphase 1

Homologous pairs line up at the metaphase plate

What is synapsis

the pairing and physical connection of homologous chromosomes (connected by the synaptonemal complex)

What is Chiasma

The X shaped point where 2 chromosomes are touching

What is Anaphase 1

The homologues separate to opposite ends of the cell, but sister chromatids stay together

What is telophase 1

Newly forming cells are haploid (cleavage beginning)

What is interkinesis

Resting phase between meiosis 1 and 2

What happens in prophase 2?

Chromosomes Condense

What happens in metaphase 2?

Chromosomes line up at metaphase plate

What happens in anaphase 2?

Sister chromatids are separated to opposite ends of the cell

What happens in telophase 2?

Each chromosome has just one chromatid, newly forming gametes are haploid

Where is the cohesin broken down in meiosis 1

The cohesin along arms of homologous chromosomes

Where is the cohesin broken down in meiosis 2

The cohesin in the centromeric region

What is a product of meiosis?

4 haploid cells, new combinations of alleles after crossing over

What is meiotic nondisjunction

When chromosome pairs/sister chormatids dont sparate correctly during cell division

What is the genetic diversity equation for gametes?

2^n

What is n?

The haploid number, number of chromosomes in the haploid genome

Who discovered the chromosomal theory of inheritence

Walter Sutton

What is a true-breeding lineage

Groups of homozygous organisms when bred produces offspring with same trait

What is the P generation

The parental generation of a true breeding lineage

Why is the F1 generation important?

It shows dominance

Why is the F2 generation important?

This generation can indicate complete dominance through the 3:1 phenotypic ratio

What is the principle of segregation?

An individual randomly passes one allele to each offspring (the offspring has an equal chance of inheriting a particular allele)

What is complete dominance

The presence of one dominant allele means the dominant phenotype is expressed

What is the locus typically named after?

The non-wild type phenotype

What is a test cross

A way to identify the genotype of an individual with a dominant phenotype

What does a chi-squared test indicate

how well the observed data fits with the expected value

What does a low chi squared value indicate?

Difference is due to chance

What does a high chi squared value indicate

The difference was due to external factors

What is the chi squared formula

the sum of [(observed-expected)²/Expected number]

What is a pedigree?

A chart that shows familial relationships and the inheritance of a specific phenotype of interest

What does autosomal mean?

Not sex linked

What kind of phenotype is this? Skips generations, Equally likely in males and females, more likely to appear among a progeny of related individuals

Autosomal Recessive Phenotype

What is a polymer?

A chain of repeating units (monomers)

What are Nucleotides made of?

A ribose/deoxyribose sugar, nitrogenous base, and a phosphate group?

What is the difference between nucleotide and nucleoside

Nucleoside has no phosphate, nucleotide has a phosphate!

What are the measurements of DNA?

2.0 nm wide, 0.34 nm between nucleotide sequences, 3.4 nm long

Who came up with the physical structure of DNA (the measurements)

Rosalind Franklin

Who proposed the double helix model of DNA?

Watson and Crick

Where is the phosphate group located on the DNA stand?

On the 5’ end

Why are chargaff’s rules important?

It measured the ratios of nucleotide bases and found out that A bonds to T and C bonds to G

Describe the double helix model of DNA

A sugar phosphate backbone, nitrogenous bases on the inside, forming a right handed helix with a major and minor groove

How are the sugars and phosphates connected?

through a phosphodiester bond

How many H bonds are between adenine and thymine?

2 H bonds

How many H bonds are between cytosine and guanine?

3 H bonds

What are the purines

Adenine and Guanine

What are the pyrimidines (DNA and RNA)

Cytosine, thymine, and uracil

Which will be stronger: sequences rich in A-T content or G-C content

G-C because of the hydrogen bonds!

What is a SNP

A single nucleotide polymorphism

What is an INDEL

Insertion or deletions in a nucleotide sequence

How do alleles connect to nucleotide sequences?

They arise from differences in nucleotide sequences

What is methylation?

The addition of a methyl group (usually on the cytosine) at CpG sites

What does methylation do?

Decrease transcriptional activity of DNA —> less RNA —> less Protein

Is methylation in prokaryotes or eukaryotes

Eukaryotes!

What is an A form of DNA?

Its categorized by a right Handed helix model with 10.9 base pairs per turn (it is short and wide)

What is a B form of DNA?

The Watson and crick model, 10 bp per turn

What is the Z form of DNA?

Left handed helix, 12 base pairs per turn

Where is the Z form of DNA found?

In GC rich regions or temporarily in areas with active transcription

In what cases do nucleic acids pair to themselves?

If inverted complementary motifs form?

What are common structures that occur after nucleic acids pair to themselves?

Loop, Stem, Hairpin, and Bulge

What is considered the Primary structure of DNA?

The nucleotide sequence

What is considered the secondary structure of DNA?

The double helix

What is considered the tertiary structure of DNA?

The higher level of organization of the double helix