dna & chromosomes mrs. stewart honors biology central magnet school
TRANSCRIPT
DNA & CHROMOSOMES
Mrs. StewartHonors BiologyCentral Magnet
School
Standards
• CLE 3210.4.1 Investigate how genetic information is encoded in nucleic acids.
• CLE 3210.4.2 Describe the relationships among genes, chromosomes, proteins, and hereditary traits.
Objectives
• Evaluate the structure of a chromosome
• Differentiate between prokaryotic and eukaryotic chromosomes
• Infer the complexity of an organism based on chromosome number
• Identify gender based on chromosomes
How big is the unseen world of cellular biology?
• Cell Sizes – Scale
• Scale of the universe
What is DNA?
• DNA – contains all the genetic (hereditary) information necessary to build and maintain an organism
DNA and Genes
• Genes – specific sections of DNA that code for a trait
How much DNA is in most of the cells in a human body?
• Approx. 2 meters in every diploid cell
• 2 meters = ___6.5___ Feet
• Approx 6 billion base pairs of DNA per cell
• Each of us has enough DNA in our bodies to reach from here to the sun and back -more than 300 times
• How is all of that DNA packaged so tightly and squeezed into a tiny nucleus?
Activity• Materials needed:
– Yarn = DNA– Easter Egg = Nucleus
• Question: What do the differently colored sections of yarn relate to in DNA?
• Mission: Make all the DNA fit into the nucleus in a way that it would still be “organized”
ChromatinDefinition:
Histones:
DNA that is tightly wrapped around proteinsfound in the nucleus of Eukaryotic cells
A sphere-shaped protein that DNA wraps aroundoNot found in Eubacteria
Chromosome Vs. Chromatin
• Chromosomes are only present during cell division.
• In between cell divisions, chromosomes are unraveled and called Chromatin
Chromosome Vs. Chromatin
• Chromosome:
• Chromatin:
Tightly coiled DNA & proteins during cell division; DNA cannot be “read” while in this form.
Loosely coiled DNA & proteins during the cell’s life other than cell division. DNA can be “read” to direct activities of the cell.
Chromosomes• Definition:
– Rod-shaped or X-shaped structures made of tightly coiled chromatin in preparation for the cell to divide
CH
RO
MO
SO
ME
S
Chromosomes
What do they look like?
• How many do humans have?
•They look like an “X” after the DNA has been duplicated (just before the cell divides)
•They look like an “I” after they divide and between cell divisions
23 Pairs of chromosomes (23 from mom, 23 from dad)
= 46 chromosomes
What does a chromosome look like?
Chromosomes
Centromere
Chromatids
Chromosome Terminology
• Centromere- Connecting point between two chromatids - holds the chromatids together
• Chromatids- identical strands of a duplicated chromosome – become visible at the beginning of
Mitosis or Meiosis– Contains same genetic information
on both
Prokaryotic vs. Eukaryotic Chromosomes
Prokaryotic• Circular• Only one• No histones (except
Archaebacteria)• Not in a nucleus
Eukaryotic
• Rod or X shaped• Many• Histones• In nucleus
Chromosome
Think – Pair – ShareWhich is more complex in
terms of DNA?
Think – Pair – ShareWhich is more complex in
terms of DNA?Adders Tongue Fern
OR
Human
Think – Pair – ShareWhich is more complex in
terms of DNA?
Potato
OR
Sand Dollar
Chromosome NumbersOrganism # of chromosome
Fruit Fly 8
Carrots & Lettuce 18
Cat 32
Earthworm 36
Human 46
Gorilla / Chimpanzee 48
Potatoes / Plums 48
Sand Dollar 52
Horse 64
Adder’s Tongue Fern 1262
Two Types of Chromosomes
• SEX– Determine the gender of the individual – Carry a few other traits– 2 out of our 46 chromosomes
• AUTOSOMES– Carry most of the traits that we inherit– 44 of the 46 chromosomes
SEX Chromosomes
• XX =
• XY =
HOMOLOGOUS CHROMOSOMES
• A pair of autosomes that are the same size and shape and code for the same genes
• One comes from ____________• One comes from ____________
• Humans have 44 autosomes, so they have 22 pairs of homologous autosomes
MomDad
KARYOTYPE
• A picture taken from a microscope of all the chromosomes within a cell. The chromosomes are then arranged in homologous pairs and given a set of numbers
Diploid vs Haploid Cells
Diploid Haploid
Description Both sets of homologous
chromosomes present
Only one of each homologous chromosome
present
Type of Cell All cells but sex cells (egg or
sperm)
Only sex cells- Egg or Sperm
Abbreviation 2n 1n
Standards
• CLE 3210.4.1 Investigate how genetic information is encoded in nucleic acids.
• CLE 3210.4.2 Describe the relationships among genes, chromosomes, proteins, and hereditary traits.
Objectives
• Evaluate the structure of a chromosome
• Differentiate between prokaryotic and eukaryotic chromosomes
• Infer the complexity of an organism based on chromosome number
• Identify gender based on chromosomes
Exit Ticket
• Socrative.com
• Room Number: Stewart348