Download Unit 3 Genetics and Heredity Study Guide

Ms. Edwards (Life Science)
Unit 15
Genetics and Heredity Study Guide
1
Mendel’s Work
Heredity-- ____________________________________________________

Trait_ ________________________________________________________.

Genetics _____________________________________________________
Peas, Please!
Pea plants are self-pollinating.
 _______________________________________________________________________________________
 Mendel “crossed” pea plants by ______________________________________________________________
 Mendel crossed pea plants with opposite traits (ex. Tall & short)
Crossing Pea Plants

Purebred-- _____________________________________________________________(ex.all plants in the
“family” are short).

_______________________________________________________________________

The F1 offspring- __________________________________________________________________________

The F2 offspring -__________________________________________________________________________

In all of Mendel’s crosses, ___________________________________________________________________

In the ________ generation, the “_____________” form of _________________________________________
__________________ in about ____________ of the plants.
Mendel’s Conclusions:
1. ______________________________________________________________________________________
2. _____________________________________________________(one from male parent, one from female)
3. ______________________________________________________________________________________
More Lingo……..

Gene _____________________________________________________________________
Alleles-- ___________________________________________________________________ (ex. Tall and
short alleles for the “height” gene)

________________________________________________________________________________________

An organism’s traits are controlled by the ____________________________ it inherits from its parents.
Dominant vs. Recessive

Dominant Allele-- ________________________________________________________________________
_________________________________________________________________(represented by a capital letter)

Recessive Allele -- ________________________________________________________________________
______________________________________________________________ (represented by a lower case letter)

_______________________________________________________________________________________
____________________________________________________________________________________________
Probability
__________________________________________________________________________

2
_________________________________________________________________________________________
__________, not what will actually happen

_________________________________________________________________________________________

Punnett Square- chart that shows______________________________________________________________
Phenotypes and Genotypes
Phenotype- ____________________________________________________
Genotype- ___________________________________________________________________________________
Homozygous- ________________________________________________________________________________
(ex. SS or ss)
Heterozygous- ________________________________________________________________________________
(ex. Ss) Also called hybrids.
Codominance

In Codominance ____________________________________________________________
________________________________________________________________________________________
Meiosis ________________________________________________________( chromosome # is reduced by half)

During meiosis, the chromosome pairs separate and are distributed to two different cells.

________________________________________________________________________________________

_____________________________________________
Remember __________ (from mitosis)
Important Facts:
1. During ____________________________________________________ separate.
2. During ____________________________________________________ separate.
3. _________________________________ occurs during ________________________.
______________________________________________________________________
A Lineup of Genes
________________________________________________________ joined together like beads on a string. The
chromosomes in a pair may have different alleles for some genes and the same allele for others.
The DNA Code Chromosomes are made of DNA. Each chromosome contains thousands of genes. The sequence
of bases in a gene forms a code that tells the cell what protein to produce.
Making Proteins
During protein synthesis, the cell uses information from a gene on a specific chromosome to
make a specific protein.
•
_____________________________________________________________________________________
•
______________________________________________________________ (DNA can’t ever leave the
nucleus) ____________________________________________________________________________
Mutations
3
____________________________ can cause a cell to produce an incorrect protein, which
_____________________________________________________________________________________.
Examples of chromosome mutations: Substitution, Deletion, Addition
Mutations can be helpful or harmful.
_______________________________________________________________________________________
Whether a mutation is harmful or helpful ______________________________________________________
2 types of mutations: 1. ______________________________ 2. __________________________________
Patterns of Inheritance

Some traits are controlled by ________________________________________________________________

Other traits are controlled by ________________________________________________________________

Some traits are controlled by ________________________________________________________________
Single Genes with 2 Alleles Controlled by a single gene with _________________________________________
•
_______________________________________________________________(for example, tall or short)
•
Represented by the typical Punnett Square crosses that we use.
Single Genes with Multiple Alleles
Multiple Alleles ________________________________________________________________________
•
Even though a gene may have multiple alleles, ___________________________
_________________________________________________________ because chromosomes exist in pairs.
•
Example: ___________________________________________________ (A, B, AB, O)
•
_____________________________________________________________ (IA, IB, i)
•
_____________________________________________________________________________________
Traits Controlled by Many Genes
•
____________________________________________________________________, which is why there are so
many phenotypes for height.
•
At least ________________________________________________________________ in humans.
•
________________________________________________________________________________________
The Sex Chromosomes The sex chromosomes are one of the 23 pairs in each body cell.
•
_________________________________________________________________________________________
•
The sex chromosomes are __________________________________of the 23 _________________________
_____________________________________________
•
Boys ______________Girls ______________
________________________________________________________________________________________
Sex-Linked Genes
-- those that are_____________________________________________________________
•
Traits controlled by sex-linked genes are called sex-linked traits.
•
_____________________________________________________(carried on the X chromosome, recessive)
4
Inheritance of Colorblindness
•
Carrier—person who _______________________________________ allele for a trait and
_______________________________________
•
_________________________________________ controlled by recessive allele
____________________________________________
•
__________________________________________________________________________________
•
__________________________________________________________________________________
The Effect of the Environment
_____________________________________________________________________________________
______________________________ Environmental Factors—diet, practice, exercise
Human Genetic Disorders
Genetic Disorder _________________________________________________________________________
•
Causes:
1. __________________________________________________________________________
2. __________________________________________________________________________
•
Karyotype ________________________________________________________________________________
Genetic Disorders
Cystic Fibrosis- body produces ____________________________________________ in lungs and intestines
•
____________________________________________________________________
•
____________________________________________________________________
(3 bases are removed from a DNA strand)
Sickle Cell Disease- ___________________________________________________________
•
____________________________________________________________________________
•
Sickled RBC’s clog arteries
•
______________________________________________________________________________
•
Must have 2 sickle cell alleles to have the disease
Hemophilia ____________________________________________________________________
•
______________________________________________________________________________
•
Caused by ______________________________________________________________________
•
Sex-linked, so it ____________________________________________________ than females
Down Syndrome- _____________________________________________________________________
Most often _____________________________________________________________during meiosis.