Principles of Biology: Lab 9 Insect GENEration instructions and grading rubric

Description

Lab 9 Insect GENEration instructions and grading rubric

Purpose: Lab 9  is based on Module 10 trait inheritance of genetic and phenotypic traits and allows practice of Punnett square analysis and observance of the inheritance of genotypic traits resulting phenotypic traits expressed by the inherited genes. Parental genotype and phenotype are provided to use to make a baby insect offspring. Practice in the lab includes Punnett Square analysis to determine offspring genotype and phenotype.

Instructions: Student completes the lab following the instructions provided and submit their work to Assignment Lab 9 Insect GENEration by November 3, 2021 11PM.

The lab report will include the following completed work:

1. Identification of the coin side that represents DOM and rec alleles. See Part A page 2.
2. Completion of matching vocabulary. See Part B page 2.
3. Completed Table II Offspring genotype and phenotype. See page 5.
4. Drawing of baby insect within the lab report. See page 6.
5. Completed questions 1-6. See page 7.

Background to do crosses to make insect babies: In this activity you will determine the genotypic and phenotypic traits inherited by an offspring from its parents using random coin flipping.

The insect parents have a small genome consisting of the following nine (9) genes as follows:

1. Thorax (LARGE or small)
2. Legs (LONG or short)
3. Foot pads (PRESENT or not present)
4. Humps (TWO or three humps on thorax)
5. Wing shape (ROUND or pointy)
6. Abdomen (WITH or without stinger)
7. Antennae on head (STRAIGHT or spiral)
8. Eyes (ROUND or long)
9. Mouthparts (LONG or short)

The phenotype of this insect offspring is determined by the genotype inherited from both its parents. You will consider the nine different traits, each of which is determined by a single different gene. Each parent is heterozygous for each of nine different genes so they have a dominant form and recessive form of each gene. Since each parent is heterozygous for each gene, either allele may be passed on to any given reproductive cell (sperm or egg). You will flip a coin to represent the random process, which determines whether a dominant or recessive allele is inherited by the offspring. Since each parent passes only one allele for each gene, you will need to flip the coin twice for each gene being considered (once for each parent).

One side of the coin will represent the dominant allele (which is always capitalized and written in this case as DOM). The other side represents the recessive allele (which is always in lower case and written in this case as rec). The practice follows Gregor Mendel’s method used in his Pisum sativum (pea plant) experiments. The double flipping allows for each allele from maternal genome (in egg) and paternal genome (in sperm) to produce the offspring. Each parent can contribute either a dominant allele (example – D)  or a recessive allele (example  – d). In this example, there is a 50% chance that either the dominant allele D or the recessive allele will be carried by each gamete (sperm or egg) produced through meiosis.

Continuing with this example, the possible combinations of gene forms, or genotype, and the phenotypes are shown in the Table I.

Table I Explanation of genotype and pentotype using Mendel’s writing convention

Genotype	Genetic Term	Descriptive Term	Phenotype (trait that appears)
DD	homozygous dominant	pure dominant	dominant trait
dd	homozygous recessive	pure recessive	recessive trait
Dd	heterozygous dominant	hybrid	dominant trait

Examples based on Table I: An offspring inheriting the genotype DD or Dd will show the dominant trait phenotype since the dominant characteristic is the one expressed. An offspring inheriting the genotype dd will show the recessive trait phenotype. In this example you have not been given the trait.

You will be given genotype information for each of the 9 genes (see page 1) using capitalized and lower case letters, which will tell you which allele is dominant and which is recessive. A>Student step to do: Identify the coin side that represents DOM and rec alleles:

Part A. Record the coin side that determines the dominant (DOM) or recessive (rec) allele after you flip the coin.

Heads:_____________________ (DOM or rec)

Tails:______________________ (DOM or rec)

 

Part B. Complete Vocabulary Matching: Match the following genetics terms to their proper definitions. Definitions may be used more than once.

See next page for choices to choose from.

1. _____ dominant allele
2. _____ phenotype
3. _____ homozygous/homozygote
4. _____ genotype
5. _____ gene
6. _____ heterozygous/heterozygote
7. _____ allele
8. _____ recessive allele

 

1. an individual’s observable traits, such as height, eye color, or blood type; outward expression of the genotype
2. having two copies of the same allele for a trait
3. the allele that can be masked by another allele when present; only appears in the phenotype if the genotype is homozygous
4. an individual’s collection of genes; genetic contribution to the phenotype
5. the genetic information for each form of a trait; one of two versions of a gene
6. having two different alleles for a trait
7. the basic physical unit of inheritance; passed from parents to offspring and containing the information needed to specify traits
8. the allele that masks another allele when present; always appears in the organism’s phenotype

Part C. Procedure how to complete the student work sheet

Example below: The student flipped the coin and for Humps genotype trait found each allele was recessive so these boxes were checked in the table below. This results in phenotype is 3 humps so that box is checked. Each trait genotype is determined this way by coin flipping, which will result in specific phenotype, and needs to be documented in the student work sheet.

Traits(DOMINANT or recessive)	Parent 1 Gene Check one box for each trait.	Parent 2 Gene Check one box for each trait.	Offspring Genotype Check one box for each trait.	Offspring Phenotype Check one box for each trait.
Humps TWO HUMPS or three humps	☐H þh	☐H þh	☐HH ☐Hh þhh	☐TWO HUMPS þthree humps

 

For the hump trait, the offspring genotype hh was checked since both parent coins landed with the recessive side up.  Therefore the expressed characteristic or phenotype in this offspring will be the recessive three humps.

 

Now, you will toss the coin, which will land either DOM or rec side up. Use parent coin flipping to determine the genotype all 9 genes. Check the dominant or recessive allele in the parent columns for each trait in Table II next page. Then check one box in the offspring genotype column and phenotype column.

 

Table II. Offspring genotype and phenotype depend on parental genotypes and phenotypes

Traits Dominant CAPITALIZED, recessive lower case.	Parent 1. ______ Check one box for each trait contributed by this parent.	Parent 2. ______ Check one box for each trait contributed by this parent.	Offspring Genotype Check one box for each trait for corresponding genotype.	Offspring Phenotype Check one box for each trait for corresponding phenotype.
Thorax
Thorax LARGE or small	o  T o  t	o  T o  t	o  TT o  Tt o  tt	o  LARGE o  LARGE o  small
Legs LONG or short	o  L o  l	o  L o  l	o  LL o  Ll o  ll	o  LONG o  LONG o  short
Foot pads PRESENT or not present	o  F o  f	o  F o  f	o  FF o  Ff o  ff	o  PRESENT o  PRESENT o  not present
Humps TWO or three humps on thorax	o  H o  h	o  H o  h	o  HH o  Hh o  hh	o  2 HUMPS o  2 HUMPS o  3 humps
Wing shape ROUND or pointy	o  W o  w	o  W o  w	o  WW o  Ww o  ww	o  ROUND o  ROUND o  pointy
Abdomen
Abdomen WITH or without stinger	o  A o  a	o  A o  a	o  AA o  Aa o  aa	o  ABDOMEN with STINGER o  ABDOMEN with STINGER o  abdomen without stinger
Head
Antennae STRAIGHT or spiral	o  N o  n	o  N o  n	o  NN o  Nn o  nn	o  STRAIGHT o  STRAIGHT o  spiral
Eyes ROUND or long	o  E o  e	o  E o  e	o  EE o  Ee o  ee	o  ROUND o  ROUND o  square
Mouthparts LONG or short	o  M o  m	o  M o  m	o  MM o  Mm o  mm	o  LONG o  LONG o  short

 

 

Draw a picture of your baby insect offspring
After determining the phenotype for all nine traits by coin toss and completing Table II now draw a picture of the baby insect’s phenotype based on results of all 9 genotypes the baby inherited. I have provided Figure 1 below showing the insect body plan for head, thorax and abdomen and Table III shows where each body part goes in the insect’s body plan. 

 

Table III to Draw General Insect Body Plan
Head	Thorax	Abdomen
Eyes	Three pairs of legs	Stinger (if present)
Antennae	Foot pads (if present)
Mouthparts	Wings
	Humps

 

 

 

Draw your insect in space below. Label each phenotype trait in the drawing. The drawing does not have to be pretty or artistic, the drawing will represent the phenotype traits present in your insect baby.

 

Questions 1-6 for lab 9

5. Refer to completed Table II. Write the complete genotype of the 9 genes present in the genome of your insect offspring as one long sentence of genotypic traits.
6. Refer to completed Table II. Write the complete phenotype of your insect offspring based on the above genotype using information from completed Table II.
7. Write the dominant genotype traits and dominant phenotype traits present in your insect offspring.
8. Write the dominant and homozygous genotype and phenotype traits present in your insect offspring.
9. Write the recessive genotype and phenotype traits present in your insect offspring.

6. Explain why an insect offspring may not inherit round wing phenotype when both its parents have the round wing phenotype. Draw a Punnett square to show your answer.