Genetics and Heredity

GENETICS

7.4 Human Genetics and Pedigrees

KEY CONCEPT

A combination of methods is used to study human
genetics.

7.4 Human Genetics and Pedigrees

• Human genetics follows the patterns seen in other

organisms.

• The basic principles of genetics are the same in all sexually

reproducing organisms.
– Inheritance of many human

traits is complex.

– Single-gene traits are

important in understanding
human genetics.

7.4 Human Genetics and Pedigrees

• Females can carry sex-linked genetic disorders.

• Males (XY) express all of their sex linked genes.
• Expression of the disorder depends on which parent carries

the allele and the sex of the child.

X

Y

What is a Pedigree?

• A chart that shows how a trait is inherited

within a family over several
generations.

• Each generation is represented by Roman

numerals and each individual in each
generation is numbered left to right.

• We can use a pedigree chart and key to

determine the genotype and phenotype
of the family members and the genetic
inheritance patterns of traits can be
tracked.

Multiple Choice

What is this?

• Pedigree

• Karyotype

• Venn diagram

• Punnett Square

Symbols Used in Pedigrees

•Circles represent females
•Squares represent male
•Horizontal lines represents mating/marriage
•Vertical lines represents children

• Unshaded represents unaffected individuals

• Fully Shaded represents affected individuals

• Half-shaded represents carriers

Parts of a
Pedigree

Unaffected

Female

Unaffected

Male

Mating

Offspring

Affected
female
offspring

Unaffected

male offspring

Multiple Choice

What does a filled in square represent?

• Not affected Female

• Not affected Male

• Affected Male

• Affected Female

Multiple Choice

How many generations are shown in this pedigree?

• 1

• 2

• 3

• 4

Multiple Choice

What does an open circle represent?

• Not Affected Male

• Not Affected Female

• Affected Male

• Affected Female

Multiple Choice

How many kids did the mother and father from the first generation have?

• 2

• 4

• 5

• 6

7.4 Human Genetics and Pedigrees

• A pedigree is a chart for tracing genes in a family.

• Phenotypes are used to infer genotypes on a pedigree.
• Autosomal genes show different patterns on a pedigree

than sex-linked genes.

7.4 Human Genetics and Pedigrees

• If the phenotype is more common in males, the gene is

likely sex-linked.

Multiple Choice

What is the pattern of inheritance shown in this pedigree?

• autosomal dominant

• autosomal recessive

• sex-linked dominant

• sex-linked recessive

Multiple Choice

Analyze the following pedigree. What type of inheritance pattern is shown?

• autosomal dominant

• autosomal recessive

• sex-linked dominant

• sex-linked recessive

Multiple Choice

For the pedigree below, shaded symbols represent afflicted people. Males are squares; females are circles. If the trait is a sex-linked trait carried on the X chromosome, what is true about the mother represented by circle 1?

• She has the genotype XXY.

• She has two alleles for the disorder.

• She is a carrier for the disorder.

• She has no alleles for the disorder.

Multiple Choice

The trait in pedigree in Figure 14–5 has two alleles: P (dominant) and p (recessive). The black symbols show the dominant phenotype, and the white symbols show the recessive phenotype. What is the genotype of individual number 1?

• Pp

• P

• p

• PP

Multiple Choice

How many generations are shown in the pedigree below?

• 2

• 4

• 6

• 8

7.4 Human Genetics and Pedigrees

• Several methods help map human chromosomes.

• A karyotype is a picture of all chromosomes in a cell.

X Y

7.4 Human Genetics and Pedigrees

• Karyotypes can show changes in chromosomes.

– deletion of part of a chromosome or loss of a

chromosome

– large changes in chromosomes
– extra chromosomes or duplication of part of a

chromosome

Multiple Choice

Examine the pedigree below. Identify the type of inheritance pattern shown in the pedigree.

• Autosomal dominant

• Autosomal recessive

• X-linked recessive

• X-linked dominant

Multiple Choice

By looking at the chromosomes is this individual biologically male or female? How do you know?

• Female, because they have two X chromosomes

• Male, because they have one X and one Y chromosome

Multiple Choice

What is the mutation in this persons chromosomes?

• There is only one X

• 7 is shaped like a hockey stick

• There's an extra 21

• 1 is too curved

Multiple Choice

This is called Turners syndrome, can you notice the mutation in the chromosomes?

• Both chromosomes 1 are bent

• There are too many chromosomes

• There are too many of chromosome 3

• There is no Y chromosome

Multiple Choice

These are the chromosomes of someone with Kleinfelters syndrome. What is different about their chromosomes?

• There is only one Y chromosome

• One of the 5th chromosomes is too curved

• There is an extra X chromosome

• There are too few chromosomes

Multiple Choice

This person has Angel Mans syndrome. What is different about their chromosomes?

• Chromosome 1 is misshapen

• Chromosomes 21 is too small

• They are missing one of chromosome 15

• Chromosomes 7 and 8 look weird

Multiple Choice

Based on the karyotype, can you guess the name of this genetic disorder?

• Curvy 3

• Jacob's syndrome

• Triple X

• Superwoman syndrome

Multiple Choice

This is known as Edwards Syndrome, can you identify the chromosomal mutation?

• Chromosomes 1 and 2 are bent

• There is no Y chromosome

• This persons chromosomes are normal

• There are 3 of chromosomes 18

Some traits include:

People in a family may have things
in common. They can share traits.

You can inherit traits from your

parents.

Eye Color

Hair color

Skin Color

Body Shape

What is
GENETICS?

The study of how
traits are inherited

through the

interactions of genes.

Inheritance or Heredity

The passing of traits from parent to offspring

OFFSPRING

Another name for the
children of a male and
female parent.

What is a GENE?

▣
The material that
controls which
traits are
expressed in an
organism

▣
Genes come in
pairs and
offspring inherit
one copy of each
gene from each
parent

HALF OF YOUR GENES
COME FROM YOUR
MOTHER, HALF COME
FROM YOUR FATHER

Inside each nucleus of a cell are thread-like structures

known as ____________________. Chromosomes come

in ____________. Individuals usually have _________

copies of each chromosome, one from each parent.

pairs

two

HOW ARE TRAITS DETERMINED?

chromosomes

HOW ARE TRAITS DETERMINED?

_________, also known as the

molecule of life, is found within

chromosomes. A __________ is a

short segment of DNA. Genes

contain instructions that

make ____________, which

determine ___________.

DNA

gene

proteins

traits

Multiple Choice

Where is your DNA found?

• Only in special cells in our body.

• In every cell in our body

• In the cytoplasm of our cells

Multiple Choice

How many chromosomes do we have?

• 23

• 12

• 32

• 104

What if they Reproduced?

What if they Reproduced?

Think Pair Share

1. What did you notice?

2. What did these examples tell you

about how offspring get their
traits?

Individuals inherit ________ forms of each

__________, one from each parent. The

different variations of a gene are known as

___________. Alleles are represented with

lowercase and uppercase ____________.

two

gene

alleles

letters

To show the different forms of a gene, color each set of

alleles on the chromosome a different color.

DOMINANT GENES

● ____________ expressed when present

● Shown as ____________ letters

● Example:

Always

= DOMINANT

capital

Multiple Choice

Why do we see Alleles as pairs?

• That is just how it is done

• Scientist have only found two so far

• We get one from each parent

RECESSIVE GENES

● Expressed if ______ copies are present

● Shown as ____________ letters

● Example:

two

=recessive

lowercase

ALLELE

Alleles are different combinations of a gene

Allele Pairs

BB

Homozygous

bb

Homozygous

Bb

Heterozygous

The genotype is the ____________ makeup

of an individual. In other words, it is the pair

of _____________ an individual inherits from

their parents.

GENOTYPES

genetic

alleles

Note: Always write the dominant (capital)

letters first when writing genotypes

EXAMPlE GENOTYPES

The phenotype is the observable ___________

or characteristics determined by the

genotype. For example, ______________

is a phenotype.

PHENOTYPES

traits

eye color

EYE COLOR

EXAMPlE PHENOTYPES

Multiple Choice

Which one is a phenotype?

• Bb

• AA

• cc

• tall

Multiple Choice

changes in DNA are called

• Ninja Turtles

• oopsies

• mutations

Multiple Choice

Heredity is the passing of traits from _____________________ to _____________________

• predators to prey

• water to rain

• parents to offspring

Multiple Choice

He is known as the father of modern day genetics.

• Santa Claus

• Charles Darwin

• Gregor Mendel

Multiple Choice

Which of these represents a female?

• XX

• XY

• YY

Multiple Choice

A dominant trait shows up ________ than a recessive trait.

• more often

• less often

• equally

Multiple Choice

___________________________ is the study of how traits are passed on, or inherited.

• Biology

• Dancing

• Genetics

Multiple Choice

This is the basis of heredity and is made of DNA.

Multiple Choice

We have 46 of these and they are found in the nucleus.

Multiple Choice

Alleles are sequences of DNA that determines things like

Multiple Choice

Who uses DNA to solve crimes?

Multiple Choice

____ allows there to be differences in the population.

Multiple Choice

What is this a picture of?

• Bugs on sticks

• Cladogram

• Family Tree

Multiple Choice

The nodes in a cladogram represent a common

• time

• ancestor

• point

Multiple Choice

Which trait is present for the lizard, hamster, and monkey?

• claws

• fur

• thumbs

Multiple Select

Which animals DO NOT have thumbs?

Multiple Choice

Binomial Nomenclature is

• a two name system to identify organisms.

• a type of bicycle

• a three name system to identify organisms.

Multiple Choice

Which kingdom would this organism belong to?

• animal

• protist

• fungi

Multiple Choice

Which kingdom would this organism belong to?

• plant

• monera

• fungi

Multiple Choice

Homozygous means

• One allele from father, and one from mother

• two alleles from one parent

• two identical alleles of a gene

Multiple Choice

A trait is dominant if

• the person has two copies of the gene

• If the person has one copy of the gene

Multiple Choice

Heterozygous means

• having two different genes

• having two different alleles of the same gene

• having two alleles from one parent

• having two alleles from both parents