DNA- Chapter 2

Chromosome are made up of

DNA Double Strand & Packaging Proteins

What are the 3 steps to turn DNA into a Chromosome

1) Nucleosome

2) Supercoiling

3) Radial Loop

-146 bp wrap around a histone octamer

-“Beads on a String”

Nucleosome Forming

Small positively charged basic proteins

Histones

H2A,H2B,H3,H4

Core Histones

What is the linker DNA histone

H1

What is the fundamental unit of chromosome packaging

Nucleosome

What two factors regarding nucleosomes affect genetic function?

1) Spacing of Nucleosome
2) Structure of Nucleosomes

-Chromatin gets condensed

-100A —> 300 A

Nucleosome Supercoiling

What histone is responsible for condensing chromatin from 100A —> 300A

H1

Chromatin that is densely compact and is not active. It cannot be transcribed.

Heterochromatin

Chromatin is not densely compact and is extremely active. It is actively transcribed.

Euchromatin

-Nonhistone proteins tether the 300A fibers into structural loops

Radial Loop Scaffold

A protein that further condenses chromosomes into a compact bundle for mitosis.

Condensins

What is revealed in chromosomal scaffold?

Two Sister Chromatids.

The basic structural unit of eukaryotic chromatin

Core histones, and DNA from the nuclesome

Which type of proteins organize and compact chromosomes into higher order structures?

Nonhistone Proteins

How are chromatin distributed by weight?

-1/3 DNA, Histone, Nonhistone

Chromosome scaffolding, chromosome segregation (kinetochore), chromosome replication (DNA Polymerases), & active transcription are all functions of

Nonhistone proteins

Proteins that help move chromosomes along the spindle apparatus

Kinetochore protein’s

Picture of an individuals chromosome’s

Karyotypes

Karyotypes uses what type of staining dye?

Giemsa Dye

What phase do we add the Giemsa Dye

Metaphase

-3 chromosomes in the 21-slot

-”Trisomy 21”

Down Syndrome

-3 chromosomes in the 18-slot

-”Trisomy 18”

Edward’s Syndrome

-3 chromosomes in the 13-slot

-”Trisomy 13”

Patau Syndrome

3 pairs of sex cells

Klinefelter Syndrome

Missing one of the sex chromosomes

Turner Syndrome

An invasive medical procedure for obtaining fetal calls in a sample of the fluid surrounding the fetus.

Amniocentesis

What is a non-invasive way to get fetus fluid

Take blood samples from the mother after the 10th week of pregnancy.

The fluorescent method that aims to detect chromosomal abnormalities

FISH

-Each pair of chromosomes is labeled with a different color of fluorescent dye

-Used for duplication, deletion, and translocation

SKY

p Arm is

Short Arm

q Arm is

Long Arm

Centromere is in the middle

Metacentric

Centromere is just off centered

Submetacentric

Centromere is almost at the top and has the p arm just barely sticking out

Acrocentric

The centromere is completely at the top of the chromosome with no p arm showing

Telocentric

Sister chromatids are attached by a

Centromere

-2 sister chromatids= 1 chromosome

-1 from mom

-1 from dad

-Same size, same trait, different alleles

Homologous Chromosomes

Somatic Cells

-Diploid

-2n

-”Double”

Gametes

-Haploid

-n

-”Half of Double”

The union of haploid gametes to produce diploid zygotes is called

Fertilization

Chromosomes that are considered non-sex chromosomes (1-22)

Autosomes

Who discovered that there are sex chromosomes

Henking

Who discovered that the Y chromosome is for male determination

Stevens

The ends of the X and Y chromosomes are considered

PARS

What does the Male Specific Region (MSY) contain

-SRY

-3 Male fertility genes

-8 Essential genes shared with X

What is the primary determinant of maleness in a single gene

SRY

If a person is XX and has an SRY gene are they considered males?

Yes

If a person is XY and does not have SRY are they considered males?

No

The presence or absence of this chromosome determines gender in humans

Y chromosome

The ratio of X chromosomes determines gender in what species

Drosophila or Fruit Flies

-1 X present = Male

-2 or more X present = Female

Insects use what sex determination system

-XO System

-XX = Female

-XO = Male

Birds, butterflies, and moths use what system

-ZW system (flips the hetero and homo)

-ZW = Female

-ZZ = Male

Lizards and alligators sex determination process

-Temperature based

Cool Temps = Females

Warm Temps = Males

Tortoise and Turtles sex determination process

Temp based (opposites)

Cool Temps = Males

Warm Temps = Females

What is the name of the complex of DNA, Protein, and RNA found within eukaryotic chromosomes?

Chromatin

What is the basic unit of a chromatin

Nucleosome

What is the composition of the nucleosome core?

-2 H2A

-2 H2B

-2H3

-2H4

The DNA of chromosomes is organized in the form of loops with the help of protein complexes called

Cohesin

A method used to identify the locations of specific DNA sequences on chromosomes displayed in a karyotype is called

FISH

What is the name of proteins found in nucleosomes, but help to assemble them during chromosome replication?

Histone chaperone proteins

What sex chromosomes do humans with Klinefelter Syndrome have?

XXY

What sex chromosomes do humans with Turner Syndrome have?

XO

What is the function of the SRY protein?

It activates testes development

Are PAR1 & PAR2 found on both X & Y chromosomes

Yes

Drosophila embryos that are X0 develop into

Males

A fruit fly with XXY chromosomes would be

Female

An alligator egg that is incubated at warm temperatures will produce a

Male

A female bird will have the sex chromosomes of

ZW