Campbell Biology 14Th Ed Chapt 13

Front 1

Heredity

Back 1

Transmission of traits from one generation to the next

Front 2

Variation

Back 2

Demonstrated by the differences in appearance that offspring show from parents and siblings

Front 3

Genetics

Back 3

Scientific study of hereditary and variation

Front 4

Offspring acquire genes from parents by...

Back 4

Inheriting chromosomes

Genes are inherited, not physical characteristics

Front 5

Units of heredity...

Back 5

Genes

Made up of segments of DNA

Passed on to the next generation via reproductive cells (gametes)

Front 6

Reproductive cells

Back 6

Gametes

Sperm and eggs

Front 7

Somatic cells

Back 7

All cells of the body except gametes and their precursors

Front 8

Chromosomes

Back 8

Humans have 46 in the nuclei of their somatic cells

Most DNA is packaged in chromosomes

Front 9

Locus

Back 9

A genes specific position along a chromosome

Front 10

Asexual reproduction

Back 10

Genes are passed on to offspring without the fusion of gametes

Multicellular organisms are capable of this like an amoeba

Reproducing this way creates a clone (genetically identical)

Front 11

Sexual reproduction

Back 11

2 parents give rise to offspring that have unique combinations of genes inherited from the two

Front 12

Humans have ——pairs of chromosomes

Back 12

23

In pairs called homologous or homologs

Front 13

Chromosomes in a pair..

Back 13

Are same length and shape

Front 14

Karyotype

Back 14

An ordered display of the pairs of chromosomes from a cell

Front 15

Sex chromosomes

Back 15

Determines sex of an individual

X and Y

Males are XY and females are XX

Front 16

Autosomes

Back 16

Remaining 22 pairs of chromosomes outside of the sex chromosomes

Front 17

Each pair of homologous chromosomes includes...

Back 17

One chromosomes from each parent

Front 18

Diploid cell

Back 18

2n

Has 2 sets of chromosomes

Diploid number for human cells is 46 (2n=46)

Front 19

Haploid cells

Back 19

A gamete ( sperm or egg) contains a single set of chromosomes

Front 20

Haploid number in humans is

Back 20

23 (n=23)

Each set of 23 consist of 22 autosomes and a single sex chromosome

Front 21

Sex chromosome in egg versus sperm

Back 21

Make-X or Y

Female-X

Front 22

Human life cycle begins when a haploid sperm fuses with a..

Back 22

Haploid egg

Front 23

Fertilization

Back 23

Union of gametes

Fusion of their nuclei

Front 24

Zygote

Back 24

Fertilized egg

Has one set of chromosomes from each parent

Produces somatic cells by mitosis and develops into an adult

Front 25

The only cells not produced by mitosis..

Back 25

Gametes which develop from special germ cells in gonads

Produced by meiosis

Reduces chromosomes to one set in each gamete

Front 26

Fertilization restores the diploid...

Back 26

Combines 2 sets of chromosomes

Front 27

Meiosis

Back 27

A type of cell division that reduces number of sets of chromosomes from 2-1

Front 28

Variety of sexual life cycles

Back 28

3 main types

Differ in timing of meiosis and fertilization

Front 29

Alternation of generation

Back 29

Plants and species of algae exhibit a second type of life cycle

Includes diploid stage (sporophyte) and haploid cells (spores)

Front 30

3rd type of life cycle occurs in

Back 30

Fungi and some protist

Front 31

Meiosis reduces the number of chromosomes sets from ____ to _____

Back 31

Diploid to haploid

Takes places in 2 consecutive cell divisions: meiosis I and meiosis II

Results in 4 daughter cells (rather than 2 in mitosis)

Each daughter cell has only half as many chromosomes as parent cell

Front 32

Stages of meiosis

Back 32

Chromosomes duplicate during interphase

Resulting sister chromatids are closely associated length-wise (chromatid cohesion)

Chromatids are sorted into 4 haploid daughter cells (different from mitosis)

Front 33

Meiosis I

Back 33

4 phases:

Prophase, metaphase, anaphase, telephase /cytokinesis

Front 34

Prophase I

Back 34

Centrosome movement, spindle formation, nuclear envelop break down

Chromosomes pair with homologous and cross over

Chiasmata occurs

Microtubles move homologous pairs toward the metaphase plate

Front 35

Metaphase I

Back 35

Pairs of homologous chromosomes are arranged at metaphase plate

Both are attached to microtubles from one pole and the other to the other

Front 36

Anaphase I

Back 36

Breakdown of proteins that hold cohesion of sister chromatid Allows to separate

Move to opposite poles

Cohesion continues at centromere

Front 37

Telephase I and Cytokinesis

Back 37

In tele: each half of cell has a complete haploid set of chromosomes

Cyto: occurs simultaneously with telephase forming 2 haploid daughter cells

Cleavage forms in animals, in plants-a cell plate

In some species chromosomes deco dense and nuclear envelope forms

Front 38

Chiasmata

Back 38

X-shaped regions on homologous pair where crossovers occurred

In prophase I

Front 39

Crossing over

Back 39

Chromosome pairs align gene to gene and then

dNa molecules of nonsister chromatids are broken and rejoined together

Front 40

Prophase II

Back 40

Spindle apparatus forms

Chromosomes of 2 chromatids associated at centromeres moved by microtubles

Front 41

Metaphase II

Back 41

Chromosomes are at metaphase plate

Due to crossing over in meiosis I, sister chromatids are not genetically identical

The kinetochores are attached to microtubles

Front 42

Anaphase II

Back 42

Breakdown of proteins sister chromatids together at centromere

Separate and move towards opposite poles as individual chromosomes

Front 43

Telophase II & cytokinesis

Back 43

Chromosomes begin condensing

Nuclei form

Cytokinesis begins

The meiotic division of one parent cell produces 4 daughter cells each with a haploid set of chromosomes

The 4 daughter cells are genetically distinct form one another and the parent cell

Front 44

Genetic variation

Back 44

Mutations (change in DNA) are original source of genetic diversity

Mutations create different versions of genes called alleles

Reshuffling of alleles during sex reproduction produces genetic variation

Front 45

Three ways for genetic variation

Back 45

1. Independent assortment of chromosomes

2. Crossing over

3. Random fertilization

Front 46

Crossing over and synapses during prophase I part 1

Back 46

1. Homologs are aligned.

DNA molecules on nonsister (one mom, one dad) chromatids are broken and start to condense

Front 47

Crossing over and synapses during prophase I part 2

Back 47

2. Zipper like structure called synaptonemal complex forms

Attached one homolog to the other

Front 48

Crossing over and synapses during prophase I part 3

Back 48

Synapsis (green-connecting)

DNA breaks are closed up so that each end is joined with the corresponding segment of the nonsister chromatid

Front 49

Crossing over and synapses during prophase I part 4

Back 49

These crossover points become visible as chiasmata (sing.=chiasma)

Synaptonemal complex dissembles

At least one crossover per pair must happen in order for homologous pair to stay together

Front 50

Mitosis vs meiosis

Back 50

Differ genetically vs genetically identical

Reduces the number of chromosomes sets from 2 to 1 vs conserves the number of chromosome sets

3 events unique to meiosis

Front 51

Anaphase II

Back 51

Breakdown of proteins sister chromatids together at centromere

Separate and move towards opposite poles as individual chromosomes

Front 52

Telophase II & cytokinesis

Back 52

Chromosomes begin condensing

Nuclei form

Cytokinesis begins

The meiotic division of one parent cell produces 4 daughter cells each with a haploid set of chromosomes

The 4 daughter cells are genetically distinct form one another and the parent cell

Front 53

Each daughter cell is

Back 53

Genetically distinct from others and parent cell

Front 54

Each gene on one homolog

Back 54

Is aligned precisely with the corresponding allele of that gene on the other homolog

ie: eye color match eye color

Front 55

Independent assortment of chromosomes

Back 55

Homologous pair of chromosomes orient randomly at metaphase I

Sorts maternal and paternal chromosomes homologs into daughter cells independent of the other pairs

Number of possible combinations: 2^n so In humans this is 2^23

Front 56

Crossing over

Back 56

Recombinant chromosomes: chromosomes that carry genes from two different parents (mix DNA from each parent into a Sinhalese chromosome)

Average of 1-3 crossovers in humans

Front 57

Crossing over and synapses during prophase I part 3

Back 57

Synapsis (green-connecting)

DNA breaks are closed up so that each end is joined with the corresponding segment of the nonsister chromatid

Front 58

Crossing over and synapses during prophase I part 4

Back 58

These crossover points become visible as chiasmata (sing.=chiasma)

Synaptonemal complex dissembles

At least one crossover per pair must happen in order for homologous pair to stay together

Front 59

Mitosis vs meiosis

Back 59

Differ genetically vs genetically identical

Reduces the number of chromosomes sets from 2 to 1 vs conserves the number of chromosome sets

3 events unique to meiosis

Front 60

Dominant alleles that cause disease

Back 60

Rare

Arise by mutation

Lethal dominant alleles kill offspring before they can mature and reproduce, allele will not be passed on to future generations

Front 61

Chorionic villus sampling (CVS)

Back 61

8th-10th week

Alternative to amniocentesis

Placenta is removed and tested

Front 62

Cell-free fetal DNA (off DNA)

Back 62

Isolation of fetal cells or DNA from mothers blood

10 weeks

Front 63

Ultrasound and fetoscopy

Back 63

Visually assess health of fetus

Front 64

Phenylketonuria (PKU)

Back 64

A recessive inherited disorder that occurs in one of every 10-15,0000 births in US

Front 65

Extra

Back 65

O

Front 66

Extra

Back 66

O

Front 67

Achondroplasia

Back 67

A form of dwarfism caused by a rare dominant allele (chr 4)

Heterozygous individuals have the phenotype

Front 68

Huntington’s disease

Back 68

Degenerative disease of the nervous system

No phenotype effects until age 35/40.

Once the deterioration of nervous system begins, condition is irreversible and fatal

Mutated copy of gene for a protein called huntingtin (chr 4)

Front 69

Percentage child will inherit Huntington’s disease from parent who has the allele

Back 69

50%

Front 70

Dominant allele

Back 70

I

Front 71

Multifactorial disorders

Back 71

Many diseases have both genetic and environmental components

Genotype typically polygenic

No matter what genotype, lifestyle has an affect on phenotype

Front 72

The best public Heath strategy is education about relevant environmental factors and promotion of healthy behaviors

Back 72

Preventive healthcare

Front 73

Using family histories genetic counseling helps couples determine odds that their children will have genetic disorders

Back 73

It is important to remember that each child represents an independent event

ie: John and carol: to determine if carriers, couple would be either AA or Aa.

Each have 2/3 chance so 2/3x2/3x1/4(chance of 2 carriers having a child with disease)= 1/9 chance they will have

Front 74

Testing for carriers

Back 74

Growing number of diseases are tested

Test enable people to make informed decisions

Raises issues as to whether affected individuals fully understand their genetic test results

Front 75

Amniocentesis

Back 75

Fetal testing for some genetic disorders

14th-16th week

Front 76

Dominant alleles that cause disease

Back 76

Rare

Arise by mutation

Lethal dominant alleles kill offspring before they can mature and reproduce, allele will not be passed on to future generations

Front 77

Chorionic villus sampling (CVS)

Back 77

8th-10th week

Alternative to amniocentesis

Placenta is removed and tested

Front 78

Cell-free fetal DNA (off DNA)

Back 78

Isolation of fetal cells or DNA from mothers blood

10 weeks

Front 79

Ultrasound and fetoscopy

Back 79

Visually assess health of fetus

Front 80

Dominant allele

Back 80

I

Front 81

Extra

Back 81

O

Front 82

Extra

Back 82

O

Front 83

Using family histories genetic counseling helps couples determine odds that their children will have genetic disorders

Back 83

It is important to remember that each child represents an independent event

ie: John and carol: to determine if carriers, couple would be either AA or Aa.

Each have 2/3 chance so 2/3x2/3x1/4(chance of 2 carriers having a child with disease)= 1/9 chance they will have

Front 84

Huntington’s disease

Back 84

Degenerative disease of the nervous system

No phenotype effects until age 35/40.

Once the deterioration of nervous system begins, condition is irreversible and fatal

Mutated copy of gene for a protein called huntingtin (chr 4)

Front 85

Amniocentesis

Back 85

Fetal testing for some genetic disorders

14th-16th week

Front 86

Chorionic villus sampling (CVS)

Back 86

8th-10th week

Alternative to amniocentesis

Placenta is removed and tested

Front 87

Multifactorial disorders

Back 87

Many diseases have both genetic and environmental components

Genotype typically polygenic

No matter what genotype, lifestyle has an affect on phenotype

Front 88

The best public Heath strategy is education about relevant environmental factors and promotion of healthy behaviors

Back 88

Preventive healthcare

Front 89

Using family histories genetic counseling helps couples determine odds that their children will have genetic disorders

Back 89

It is important to remember that each child represents an independent event

ie: John and carol: to determine if carriers, couple would be either AA or Aa.

Each have 2/3 chance so 2/3x2/3x1/4(chance of 2 carriers having a child with disease)= 1/9 chance they will have

Front 90

Extra

Back 90

O

Front 91

Extra

Back 91

O