Monday, April 23, 2012Homework: none

Plan:1) Mitosis/Meiosis/Karyotype Checkup2) Review MendelSim data from Friday3) MendelSim Questions4) Heredity/genetics Notes

CheckupBe sure to write your VERSION A or B on your answer sheet.

Record all answers #1-18 on the answer sheet.

MendelSim Data ReviewGoes in entry from Friday-Entry 39: MendelSim Simulation- 4/20/12

Parent 1 Parent 2 Offspring (after 50 crosses)

Red Blue

Data Table 1: Pure Red X Pure Blue

Parent 1 Parent 2 Offspring (after 50 crosses)

Red Blue

Data Table 2: Cross of Two Red Offspring

Data Table 3: Cross of Two Blue OffspringParent 1 Parent 2 Offspring (after 50 crosses)

Red Blue

Red Blue

Red Red

Blue Blue

50 0

38 12

This one varied

0 50

PARENT 2BLUE

X 50 (ALL) RED OFFSPRING

=

PARENT 1RED

PARENT 2RED

X =

38 RED 12 BLUE

X = 50 (ALL) BLUEOFFSPRING

PARENT 1RED

PARENT 1BLUE

PARENT 1BLUE

TAPE in these questions and answer them in your logbook

1. What is the trait we observed?2. What are the results of crossing the red

flowers with the blue flowers?3. Based on the results, what do we know about

the flower color gene?4. What are the results for the second crossing

—red crossed with red?5. The flowers in the second crossing look red—

but what do we know about their genetics?6. What happened to the blue trait and how did

it show up again in the third generation?

Make an entry- Heredity and Genetics 1- 4/23/12This is a “see attached” entry-

First, some information we already know…

Chromosome structure- DNA

• Chromosomes = long pieces of DNA

Chromosomes come in pairs (one from mom and one from dad)

Cut out from picture and match each in pairs

Chromosomes have genetic information and are passed to offspring

chromosomes

Dividing onion cells

chromosomes

nucelus

cell wall

Chromosome structure - genes

Human chromosome # 7

• Contains about 1,800 genes

• Contains over 150 million nucleotides

Link to view genes and DNA sequence

• Parts of chromosomes that code for proteins are called genes

• Genes, and specifically the proteins made from them, help determine your characteristics RGene for

RED flowers

How does your DNA determine your traits?

DNA mRNA protein Observed trait

transcr

iption

transla

tion

Example1: A person has DNA that has instructions to make LACTASE (a protein) which allows them to digest milk

Example 2: The Labrador Retriever has DNA that has the instructions to make TRP-1 which converts brown pigment to black—so they have black fur.

Trait – a characteristic of an organism– Example: “flower color”

Gene – part of a chromosome that helps determine a specific trait– Example: “flower color gene”

Allele – a form of a gene – Example:• One allele is the “blue” form of the gene• One allele is the “red” form of the gene

• Humans = 23 chromosome pairs, or 46 total. We have about 24,000 genes.

Some other examples: (do not need to memorize)

• Pea flower = 7 chromosome pairs (14 total)• Fruit fly = 4 chromosome pairs (8 total) 13,601

genes identified so far!• Potato = 24 pairs (total 48)• Horse = 32 pairs (total 64)

How many chromosomes?

Chromosomes come in pairs (one from Mom and one from Dad)

• This pair of chromosomes is called a “homologous pair” because they have the same genes on them -

Flower chromosome 3

(from computer simulation)From Dad

From Mom

flower color gene

IMPORTANT: homologous pairs are NOT IDENTICAL, but they have the same genes, – Alleles can be different

flower color gene

From Dad

From Mom

“Blue” alleleof flower colorgene

“Red” alleleof flower colorgene

The combination of alleles determines the observed characteristics

Chromosomecombination

Allelecombination

Observedcharacteristic

REDallele

RED allele

REDallele

BLUE allele

BLUEallele

BLUE allele

red, red red, blue(or blue, red)

blue, blue

RED RED BLUE