Bio Chapter 9

Front 1

Inheritance

Back 1

the process by which the
characteristics of individuals are passed to their
offspring

Front 2

DNA carries genetic information in the form of...

Back 2

nucleotides

Front 3

Chromosomes are made up of...

Back 3

DNA together with proteins

Front 4

Genes

Back 4

are parts of chromosomes

Front 5

A ____ is a unit of heredity that encodes
information for the form of a particular
characteristic

Back 5

gene

Front 6

The location of a gene on a
chromosome is called its...

Back 6

locus (loci)

Front 7

Each member of a
homologous chromosome
carries the __________,
located at the same loci

Back 7

same genes

Front 8

Different nucleotide
sequences at the “same”
locus on two chromosomes
are called

Back 8

alleles

Front 9

Each cell carries ___
alleles per
characteristic, one on
each of the two
homologous
chromosomes

Back 9

two

Front 10

If both homologous
chromosomes carry the
same allele (gene form)
at a given gene locus,
the organism is
_________ at that
locus

Back 10

homozygous

Front 11

If two homologous
chromosomes carry
different alleles at a
given locus, the
organism is
_________ at
that locus

Back 11

heterozygous
(a hybrid)

Front 12

Mendel

Back 12

Experimented with pea plant inheritance
monk
in a monastery in
Brno (now in Czech
Republic) in late
1800s

Front 13

Mendel studied ____ and _____ at
the university level before becoming a
monk

Back 13

botany and mathematics

Front 14

Important aspects of pea plants

Back 14

– Pea flowers have male structures that
produce pollen (male gametes) by meiosis
– Pea flowers have female structures that
produce eggs (female gametes) by meiosis
– Pea flower petals enclose both male and
female flower parts and prevent entry of
pollen from another pea plant

Front 15

Pea flowers can ....

Back 15

Self-fertilize
Pollen from male structures
transfers to
eggs female structures within the same
flower

Front 16

Although peas can self-fertilize, plant
breeders can mate two plants by hand
causing _______.

Back 16

cross-fertilization

Front 17

Pea plants that are ______ for a
particular characteristic always produce
the same physical forms

Back 17

homozygous
Example: If a plant is homozygous for purple flowers, it
will always produce offspring with purple
flowers

Front 18

Plants homozygous for a characteristic are...

Back 18

true-breeding

Front 19

Mendel was able to mate two different plants by hand (cross-fertilization).

Back 19

Female parts (carpels) were dusted
with pollen from other selected plants
– In this way two plants can be mated to
see what types of offspring they produce

Front 20

The parents used in a cross are part of the...

Back 20

parental generation (known as P)

Front 21

The offspring of the P generation are members of the

Back 21

first filial generation (F1)

Front 22

Offspring of the F1 generation are
members of the...

Back 22

F2 generation,

Front 23

Mendel crossed a...

Back 23

true-breeding purple
flower plant with a
true-breeding whiteflower
plant (P
generation)
The F1 generation
consisted of all
purple-flowered
plants

Front 24

Mendel’s Flower Color
Experiment:
monohybrid cross

Back 24

1) crossed a
true-breeding purple
flower plant with a
true-breeding white flower
plant (P generation)
2) F1 generation consisted of all purple flowers
3) Then allowed the F1 generation to self fertilize
4) F2 were composed of ¾
purple flower plants and ¼ white flower plants
• 3:1 ratio
• Capacity to
reproduce white
flowers was only
hidden

Front 25

There are ___ alleles for a given gene
characteristic (such as flower color)

Back 25

2

Front 26

The particular combination of the two
alleles carried by an individual is called

Back 26

the genotype (PP, Pp, or pp)

Front 27

The physical expression of the genotype
is known as the

Back 27

phenotype (e.g. purple
or white flowers)

Front 28

The phenotype of the homozygous
dominant genotype

Back 28

PP is purple flowers

Front 29

The phenotype of the homozygous
recessive genotype

Back 29

pp is white flowers

Front 30

The phenotype of the heterozygous
dominant

Back 30

Pp is for purple flowers

Front 31

Mendel’s Law of Segregation

Back 31

A sperm or egg carries only one allele for each inherited character because allele pairs separate (segregate) from each other during the production of gametes.
-The separation of alleles in meiosis

Front 32

Mendel’s Flower Color Experiments: The first filial generation (F1) offspring were
produced from the fertilization of pollen and
eggs from both parents. The F1 offspring were
all?

Back 32

heterozygous (Pp)
for flower color

Front 33

When the F1 offspring
were allowed to self fertilize,
_____ types of
gametes were
produced from the Pp
parents

Back 33

4

Front 34

Combining four gametes into
genotypes in every possible way produces offspring

Back 34

PP, Pp, Pp, and pp
– Can also be
tabulated by the
genotypic fraction of
total offspring: ¼ PP,
½ Pp, and ¼ pp

Front 35

Punnett Square
Method

Back 35

predicts
offspring genotypes
from combinations
of parental gametes

Front 36

A simple
monohybrid * cross

Back 36

a cross that
provides data about
one trait – is the
simplest form of a
Punnet Square

Front 37

test cross

Back 37

used to deduce the actual
genotype of an organism with a dominant
phenotype
1. Cross the unknown dominant-phenotype
organism (P_) with a homozygous recessive
organism (pp)
2. If the dominant-phenotype organism is
heterozygous (Pp), approximately half of the
offspring will be of recessive phenotype (pp)
3. If the dominant-phenotype organism is
homozygous dominant (PP), only dominantphenotype
offspring will be produced (Pp)

Front 38

Dihybrid Cross

Back 38

Involves two different traits located on
two different chromosomes and assort
independently of the other trait

Front 39

Mendel used ______ to explain
how two pairs of genes are assorted
into gametes independently

Back 39

dihybrid crosses

Front 40

Mendel's law of independent assortment

Back 40

each pair of alleles segregates independently of other pairs of alleles during gamete formation
• Members of each pair of homologous
chromosomes are sorted into gametes at
random during meiosis

Front 41

autosomes

Back 41

(non-sex) chromosomes

Front 42

sex-linked gene

Back 42

Genes carried on
one of the sex
chromosome
(mainly the x)
– X chromosome is
much larger than the
Y and carries over
1000 genes
– Y chromosome is
smaller and carries
only a few genes

Front 43

X Chromosome

Back 43

2,300 genes
• Most genes deal with nonsexual traits
– some genes on the x-chromosome are
associated with sexual characteristics.
– distribution of body fat and hair color
– Eye color
– Color vision
– Genes located on the x-chromosomes are called
x-linked genes.
• Genes on X chromosome can be expressed

Front 44

females can be either homozygous (X1X1) or
heterozygous (X1X2) for alleles on the X
chromosomes and ______ relationships
among alleles will be expressed

Back 44

dominant versus recessive

Front 45

Males _____ all the
alleles they have on their single X
chromosome, whether those alleles are
dominant or recessive*

Back 45

express
-For this reason, in humans most cases of
recessive traits encoded by genes on the
X chromosome e.g. color blindness,
hemophilia, muscular dystrophy, occur in
males

Front 46

Sex-linked disorders appear more
frequently in ____ and often ___
generations

Back 46

males
skip

Front 47

Polygenic Inheritance

Back 47

Phenotypes produced by polygenic
inheritance are governed by the interaction
of more than two genes*
– Examples include human height, skin color,
and body build,

Front 48

Environmental Influence

Back 48

The environment can
module how genes are
expressed
– Himalayan rabbits have
the genotype for black
fur all over the body
– Black pigment is only
produced in colder
areas of the body: the
nose, ears, and paws

Front 49

Recessive Alleles Cause Some Human Genetic
Disorders

Back 49

– Albinism Results From a Defect in Melanin
Production
– Sickle-Cell Anemia Is Caused by a Defective
Allele for Hemoglobin Synthesis

Front 50

Recessive Genetic Disorders

Back 50

Heterozygous individuals are carriers of a
recessive genetic trait
• Recessive genes are more likely to occur
in a homozygous combination

Front 51

Albinism

Back 51

An allele known as TYR (for tyrosinase)
encodes a defective tyrosinase protein in
skin cells, producing no melanin
Melanin- dark pigment in skin
Tyrosinase- enzyme that produces melanin

Front 52

Sickle-Cell Anemia

Back 52

A mutant hemoglobin gene causes hemoglobin molecules in blood cells to clump together
– Red blood cells take on a sickle (crescent)
shape and easily break
– Blood clots can form, leading to oxygen
starvation of tissues and paralysis

Front 53

Hemoglobin is

Back 53

an oxygen-transporting protein
found in red blood cells

Front 54

Dominant Genetic Disorders

Back 54

1.Marfan syndrome
– disorder of the
connective tissue
• It is carried by a
gene called
FBN1, codes for
the connective
protein fibrillin-1