sample gateway genetics
TRANSCRIPT
Genetics
DNAMitosis and Meiosis
What is DNA?
DNA RNA Proteins• DNA: stored in nucleus; holds
information on making everything• Does not leave nucleus!
• RNA: carries information from DNA in nucleus to other areas
• Proteins: Help with cell processes (making energy, breaking down waste) gives traits to organism (hair color, skin texture, etc.)
DNA RNA• Transcription: makes mRNA from DNA• Occurs in the nucleus of eukaryotic cells
• Why? DNA can’t leave nucleus!• mRNA is complementary to the DNA
Thymine(Uracil) = AdenineCytosine = Guanine
DNA: TAC GAT TAC CGG GTA ACT ATA TCAmRNA: AUG CUA AUG GCC CAU UGA UAU AGU
RNA Proteins• Translation: Makes proteins from mRNA• Ribosomes read instructions on mRNA;
find correct amino acids to build proteinmRNA: AUG CUAAA: Methionine Leucine
How is DNA organized?• DNA is coiled into chromosomes before
mitosis and meiosis• A normal human has 23 pairs or 46 total
chromosomes• Each chromosome contains different
genes with information on how to create every protein needed to make a human
What is Mitosis?• Mitosis: Cell Division to create identical
copies of cells• Occurs to replace dead cells or grow
existing tissues• Result: Two identical cells• Four main phases: Prophase, Metaphase,
Anaphase, Telophase• Remember: PMAT
• FIRST: DNA Replicates• Prophase: Prepare by
condensing chromosomes, breaking down nucleus
• Metaphase: Chromosomes line up in the middle of the cell
• Anaphase: Chromosomes move apart
• Telophase: Two identical cells form
What is Mitosis?
What is Meiosis?• Meiosis: Creates gametes used for
reproduction (eggs/sperm)• Cells have half the number of
chromosomes as beginning cell• Result: Four gamete cells• Same phases as mitosis but they occur
twice
What is Meiosis?• First: DNA Replicates• PMAT I phases• DNA replication
does not occur again• PMAT II phases• Result: Four
different gametes with half normal number of chromosomes
• Why is this necessary?
Practice• Fill in the chart with the necessary
information.Mitosis Meiosis
Definition
Resulting Number
Genetically
Number of phases
List Phases
How are traits inherited?• Traits in DNA are passed from parent to
offspring• The offspring has a combination of traits
from both parents• Offspring traits can be predicted using
parent traits in a punnett square
What information do you need?• Each person’s genotype is written with
two letters• Uppercase = dominant
• if there is a dominant trait, it will always show!
• Lowercase = recessive • if there is a recessive trait, it will only show if
there is no dominant!• AA = Dominant aa = recessive• Aa = Dominant
How do you complete a punnett square?1. Add each parents genotype2. Carry letters across3. Carry letters down
AA
a
a
A A
a a
A
A
a
a
What does the punnett square tell you?• The boxes represent potential genotypes
of offspring if the two parents have offspring
• Can find ratios/percentages of the chance an offspring will have the dominant or recessive trait
Percent dominant trait?75%Ratio of dominant:recessive?3:1
Practice• Brown eyes are dominant to blue. The
father’s genotype is Bb. The mother has blue eyes.
1. Create a punnett square for the two parents.
2. What is the percent chance they will have a child with blue eyes?
3. What is the ratio of children with brown eyes versus blue eyes?