meiosis and heredity

MEIOSIS10.1

Making gametes…

http://waynesword.palomar.edu/lmexer2a.htm

Review Questions1. How many chromosomes would a sperm or an egg contain if

either one resulted from the process of mitosis?

2. If a sperm containing 46 chromosomes fused with an egg containing 46 chromosomes, how many chromosomes would the resulting fertilized egg contain? Do you think this would create any problems in the developing embryo?

3. In order to produce a fertilized egg with the appropriate number of chromosomes (46), how many chromosomes should each sperm and egg have?

46 chromosomes

46 + 46 = 92; a developing embryo would not survive if it contained 92 chromosomes.

Sperm and egg should each have 23 chromosomes.

Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htmFamily http://babyhearing.org/Parenet2Parent/index.asp

Remember from Chapter 1:CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________

REPRODUCE

ASEXUAL REPRODUCTIONBacteria reproduce using__________________________________

Budding & regeneration are used by plants and animals to reproduce asexually (mitosis)

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html

http://fig.cox.miami.edu/~cmallery/150/mitosis/c7.13.2.hydra.jpg

Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm

BINARY FISSION

BINARY FISSION & MITOSIS

Produces cells that are __________ copies of parent cell

identical

ADVANTAGES OF ASEXUAL REPRODUCTION

Can make offspring faster

Don’t need a partner

http://www.mrgrow.com/images/cutting.jpg

DISVANTAGES OF ASEXUAL REPRODUCTION

ALL ALIKE

Species CAN’T change and adapt

One disease can wipe out whole population

http://www.mrgrow.com/images/cutting.jpg

SEXUAL REPRODUCTION

Combines genetic materialfrom 2 parents (sperm & egg)so offspring aregenetically __________ from parents

DIFFERENT

Family image from: http://babyhearing.org/Parenet2Parent/index.asp

ADVANTAGES OF SEXUAL REPRODUCTION

Allows for variation in population

Individuals can be different

Provides foundation for EVOLUTION

Allow species to adapt to changes intheir environment

http://naturalsciences.sdsu.edu/classes/lab8/spindex.html

EGG + SPERM

If egg and sperm had same number of chromosomes as other body cells . . . baby would have too many chromosomes!

http://www.angelbabygifts.com/Image by Riedell Image by Riedell

http://www.acmecompany.com/stock_thumbnails/13217.forty-six_chromosomes.jpg

MEIOSIS is the way…to make cells with ½ the number of chromosomesfor sexual reproduction


HOMOLOGOUS CHROMOSOMESImage modified by Riedell • SAME SIZE

• SAME SHAPE• CARRY GENES for the SAME TRAITS

• BUT ______________! (Don’t have to have the SAME CHOICES)

http://sps.k12.ar.us/massengale/genetics%20tutorial.htm

NOT IDENTICAL

DIPLOID & HAPLOIDMost cells have 2 copies of each chromosome = ______________

(one from mom; one from dad)

All BODY (___________) cells are diploid

DIPLOID 2n

HOMOLOGOUSCHROMOSOMES

= SOMATIC

DIPLOID & HAPLOIDSome cells have only one copy of each chromosome = _____________

All sperm and egg cells are haploid

HAPLOID 1n

MITOSIS• Makes ___ cells genetically _________ to parent cell & to each other

• Makes ___ cells• Makes __________• Used by organisms to: increase size of organism, repair injuries, replace worn out cells


2identical

2n

SOMATIC (body)

MEIOSIS• Makes ____ cells genetically different from parent cell & from each other

• Makes _____ cells• Makes ______________

• Used for ____________

4

1n Germ cellsOR Gametes (sperm & eggs)

sexual reproduction


WHAT MAKES MEIOSIS DIFFERENT ?

1. SYNAPSIS & CROSSING OVER (PROPHASE I)

2. SEGREGATION & INDEPENDENT ASSORTMENT

(ANAPHASE I)

3. Skip INTERPHASE II (NO S) CELL DIVIDES TWICE, BUT…

ONLY COPIES DNA ONCE


1.Homologous chromosomes pair up during ________________

= ______________SYNAPSIS

Images modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

This group of FOUR (4)chromatids is called a_________________TETRAD

PROPHASE I

WHAT MAKES MEIOSIS DIFFERENT?

1. Exchange of DNA betweenhomologous pairs = _____________during PROPHASE I

CROSSING OVER

Allows shuffling of genetic material

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

CROSSING

OVER

Image modified by Riedell

• Allows for_________________in different combinations

• After crossing over, chromatid arms are________________ anymore


rearranging of DNA

NOT IDENTICAL


2.Separation during ANAPHASE I

INDEPENDENT ASSORTMENT

Separates gene choices and allows shuffling of genetic material

SEGREGATION &

SEGREGATION(Anaphase I)

SEGREGATION & CROSSING OVERtogether make even more combinations



http://fig.cox.miami.edu/~cmallery/150/mitosis/c13x9independent-assortment.jpg

INDEPENDENT ASSORTMENTat ANAPHASE I

Lots of different combinations are possible!This is why you don’t look exactly like your brothers and sisters even though you share the same parents!


Crossing over Segregation Independent assortment

are ALL ways MEIOSIS results in =______________________________

So daughter cells are ______________from parents and from each other

differentGENETIC RECOMBINATION


3. Skip INTERPHASE II (No S) CELL DIVIDES TWICE, BUT … ONLY COPIES ITS DNA ONCE

G1 G2S P M A T C

G1

MITOSIS:

MEIOSIS:

S G2 P M A T CP M A T C

( I )

( II )

Go to Section:

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Go to Section:

Meiosis I

Section 11-4


Meiosis I

Go to Section:

Section 11-4


Meiosis I

Go to Section:

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

Ways Meiosis is different?• Homologous pairs match up & trade DNA

(SYNAPSIS & CROSSING OVER) in PROPHASE I

•SEGREGATION

& INDEPENDENT ASSORTMENT in Anaphase I

create genetic recombination• Skipping INTERPHASE II- (Dividing TWICE but copying DNA once)

produces 1n cells

The Work of Gregor Mendel

10.2

http://www.jic.bbsrc.ac.uk/germplas/pisum/zgs4f.htm


Transmission of characteristics from _______________________is called ___________________.

The science that studies _____characteristics are _________ from onegeneration to the next is called___________________

heredity

Genetics

parents to offspring

howpassed on

The __________________ is _________________,

a monk whose _________ of genetic traits was the beginning of our _________________ of _____________________.

Gregor Mendel

http://www.jic.bbsrc.ac.uk/germplas/pisum/zgs4f.htm

Father of Genetics

study

understandinghow genes work

Mendel designed

____________ using

__________ in the

monastery garden

_______ part of flower makes

___________ (sperm)

__________ part of flower makes

_______ cells

Pea plants

Pollen

http://www.cedarville.edu/academics/education/resource/schools/chca/2scideb/debwebpv.htm

http://hus.yksd.com/distanceedcourses/YKSDbiology/lessons/FourthQuarter/Chapter11/11-1/images/MendelExperiment.gif

experiments

MALE

FEMALE

egg

In pea plants, the pollen normally joins with an egg from the _______ plant (=_______________ ) so seeds have “_________________”

Self pollination


same

ONE parent

MENDEL’S PEA EXPERIMENTS

Mendel started his experiments with peas that were _________________

= if allowed to _________________ they would produce ____________________ to themselves.


true breeding

self pollinate

offspring identical

MENDEL’S PEA EXPERIMENTSMendel ____________________making parts and ____________from _______ plant.

This allowed him to_____________ plantswith ______________ characteristics and ________ the results


different

removed pollenadded pollen

another

cross-breed

study

A _____________________ is called a ____________

Mendel ______________ in peas.

specific characteristic

trait

Pearson Education Inc,; Publishing as Pearson Prentice Hall

studied 7 traits

MENDEL’S EXPERIMENTS

____ generation (_________)

____ generation

(______= offspring)

___ generation

P1

F1

F2

parental

filial

P Generation F1 Generation F2 Generation

Tall Short Tall TallTall Tall Tall Short

Section 11-1

Principles of Dominance

When Mendel ______________ PLANTS with 2 ______________ traits:(EX: Tall crossed with short)

He always found same pattern: 1. ONLY ______ trait ____________

in the ____ generation BUT . . .

2. ___________ trait ____________ in the ____ generation

in a _________ ratio

ONE showedF1

F2

3:1

crossed PURE contrasting

Missing returned

PATTERNS ARE THE KEY

Image modified from:http://www.laskerfoundation.org/rprimers/gnn/timeline/1866.html http://www.accessexcellence.org/AB/GG/mendel.html

Mendel decided that there must be a __________________ that ________each trait and that

__________ must be able to _______ the other.

pair of FACTORS

one factor

control

HIDE

We now know that Mendel’s ________________ carried onthe pair of________________

_________________

factors are geneshomologouschromosomes

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

________ gene _______ for atrait are called ___________.ALLELES


DIFFERENT

CHOICES

__________________ = An allele that ________ the presence of another allele

__________________ = An allelethat __________________ the

presence of another allele

DOMINANT

RECESSIVE

HIDES

is hidden by

DOMINANT/RECESSIVE_____________ allele is represented by a

____________ letter.(usually the first letter of the trait)

____________ allele is represented by the SAME

_________________ letter.

EX: Tall = ______

Short =______

capital

lower-case

T

t NOT S for short

Dominant

Recessive

HOMOZYGOUSHETEROZYGOUS

When both alleles in the pair are the _______, the organism is _______________ or __________

EX: ____ or ___

When both alleles in the pair are _____________, the organism is

_________________ or _____________

Ex: ____

HETEROZYGOUS HYBRID

HOMOZYGOUS PURESAME

TT tt

DIFFERENT

Tt

PHENOTYPE/GENOTYPE

The ________________ of an organism is its _____________

The ____________ of an organism is

its _____________

GENOTYPE

PHENOTYPE

genetic makeup

appearance

Why did the recessive trait disappear in the F1 generation and reappear in the F2?

Image modified from:http://www.laskerfoundation.org/rprimers/gnn/timeline/1866.html

The pattern corresponds to the ____________ of ______________ during____________________MEIOSIS

movementchromosomes

REMEMBER

_____________

chromosomes

________________

during

ANAPHASE I

= _________________SEGREGATIONImage modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

HOMOLOGOUS

SEPARATE

____ offspring __________ an allele for tallness from their _______ parent and an allele for shortness from their ________ parent.

The F1 plants ALL ___________ but are ___________ an

allele for _________

TALL

Images from: BIOLOGY by Miller & Levine; Prentice Hall Publishing ©2006

SHORT

LOOK TALL

F1 received

carrying shortness

alleles are separated when the F1 plants ______________

When these gametes recombined to make the F2 generation, the _____________ trait _______________ in ¼ of the offspring

EXPLAINING the F1 CROSS

LAW OF ___________________SEGREGATION

Image from: BIOLOGY by Miller & Levine; Prentice Hall Publishing ©2006

recessive

made gametes

reappears

MAKING A CROSS for only a __________ trait =____________________MONOHYBRID CROSS

ONE GENE

MAKING A CROSS with ___________________=____________________DIHYBRID CROSS

TWO gene traits

LAW OF __________________________

the factors are distributed to gametes independently of other factors


Image modified from: http://anthro.palomar.edu/mendel/mendel_1.htm

PROBABILITY & PUNNETT SQUARES

10.2

Tossing Coins - Mini Activity• If you toss a coin, what is the

probability of getting heads? Tails? • If you toss a coin 10 times, how many

heads and how many tails would you expect to get? – Working with a partner, have one person

toss a coin ten times while the other person tallies the results on a sheet of paper. Then, switch tasks to produce a separate tally of the second set of 10 tosses.

1. Assuming that you expect 5 heads and 5 tails in 10 tosses, how do the results of your tosses compare? How about the results of your partner’s tosses? How close was each set of results to what was expected?

2. Add your results to those of your partner to produce a total of 20 tosses. Assuming that you expect 10 heads and 10 tails in 20 tosses, how close are these results to what was expected?

Results will vary, but should be close to 5 heads

and 5 tails.

The results for 20 tosses may be closer to the predicted 10 heads and 10 tails.

3. If you compiled the results for the whole class, what results would you expect?

4. How do the expected results differ from the observed results?

The results for the entire class should be even

closer to the number predicted by the rules of probability.

The observed results are usually slightly

different from the expected results due to

Experimental error.

It can be written as a:

Fraction ____

Percent ____

Ratio ___

____________________is the __________ that a

particular _________________

PROBABILITY

1/4

25%

1:4

likelihoodevent will occur

COIN FLIPThere are 2 possible

outcomes:

HEADS TAILS

capital

http://www.arborsci.com/CoolStuff/CoinFlip.jpg

The chance the coin will land on either one is:

____ ____ ____

Alleles segregate randomly just like a coin flip. . . So we can use probability to predict outcomes of genetic crosses.

1/2 50% 1:2

PROBABILITIES_____ outcomes ______ affect _________ones

_____________works ______ in ___________ a ________ number of events.

If last coin flip was heads… there is still a 50/50 chance the next flip will be heads too.

The more flips. . . The closer results will be to

the expected 50:50 average.

PAST DON’T FUTURE

Probability best predictinglarge

DOMINANT/RECESSIVE_____________ allele is represented by a

____________ letter.(usually the first letter of the trait)

____________ allele is represented by the SAME

_________________ letter.

EX: Tall = ______

Short =______

capital

lower-case

T

t NOT S for short

Dominant

Recessive

HOMOZYGOUSHETEROZYGOUS

When both alleles in the pair are the _______, the organism is _______________ or __________

EX: ____ or ___

When both alleles in the pair are _____________, the organism is

_________________ or _____________

Ex: ____

HETEROZYGOUS HYBRID

HOMOZYGOUS PURESAME

TT tt

DIFFERENT

Tt

PHENOTYPE/GENOTYPE

The ________________ of an organism is its _____________

The ____________of an organism is

its _____________

GENOTYPE

PHENOTYPE

genetic makeup

appearance

MAKING A CROSS for only a __________ trait =____________________

A Punnett square for a MONOHYBRID CROSS looks like this:

MONOHYBRID CROSSONE GENE

PUNNETT SQUARESare used to show possible offspring

from a cross between 2 parents

_______________ go at top and on left side

Boxes show _______________________________

T T

T

t

possible offspring combinations

Parent alleles

1. ___________ what _________________ are2. ________correct__________ square __________3. ______ possible_______________________4. ______ boxes with _____________________5. Determine ____________of_____________& ____________

STEPS FOR MAKING CROSSES

Figure out parent allelesChoose Punnett sizePut in parent gametesFill in offspring combinations probabilities phenotypes

genotypes

IN PEA PLANTS

Tall is dominant over short

TALL = ____

SHORT = ____T

tLET’S MAKE A CROSS!

PURE TALL PURE SHORTX

PURE TALL parentWhat are the parent alleles?

T T _________

T T

HOMOZYGOUS

What gametes can it make?

PURE SHORT parent What are the parent alleles?

t t _________

t t

HOMOZYGOUS


GENOTYPE _____ PHENOTYPE _______

_____ of the offspring

____ %

___/4

will be

T T

t

t

T t T t

T t T t

Tt TALL

ALL

100

4

HYBRID TALL parents What are the parent alleles?

T t _________

T t

HETEROZYGOUS


GENOTYPES

¼ = _____

½ = _____

¼ = _____

T t

T

t

T T T t

T t t t

PHENOTYPES ____ or ____% _________ ____ or ____% _________

TT

75

Tt

tt

3/41/4 SHORT

TALL25

PRACTICE MAKING GAMETES for a MONOHYBRID CROSS

Tall = ____ Round seeds = ___

Short = ____ Wrinkled seeds = ___

T

tR

r

Homozygous Tall parent =

What gametes can it produce?

What are the possible gametes?

T T

T T

PURE wrinkled parent =



rr

r r

Heterozygous Round parent =



R r

R r

Hybrid Tall parent =



Tt

T t

DIHYBRID CROSSES(2 traits)

http://mac122.icu.ac.jp/BIOBK/BioBookgenintro.html

Mendel also asked the question?

Does the gene that determines if a seedis round or wrinkled have anything todo with the gene for seed color?

Must a seed that is yellow also be round?

MAKING A CROSS with ___________________=____________________

A Punnett square for a DIHYBRID CROSS looks like this:

DIHYBRID CROSSTWO gene traits

Section 11-3

Figure 11-10 Independent Assortment in Peas

1. ___________ what _________________ are2. ________correct__________ square __________3. ______ possible_______________________4. ______ boxes with _____________________5. Determine ____________of_____________& ____________

LET’S MAKE A DIHYBRID CROSSHOMOZYGOUS

ROUND YELLOW

rryy

HOMOZYGOUSWRINKLED GREEN

Figure out parent allelesChoose Punnett sizePut in parent gametesFill in offspring combinations probabilities phenotypes

genotypes

RRYY

LAW OF __________________________

the factors are distributed to gametes independently of other factors


Image modified from: http://anthro.palomar.edu/mendel/mendel_1.htm

r r y y

HOMOZYGOUS WRINKLED GREEN

PRACTICE MAKING GAMETESWHAT ARE THE POSSIBLE GAMETES THIS PARENT CAN MAKE?

Each gamete shouldget one of each kindof gene

___________ ____________ _____________ _____________r y r y r y r y

R R Y Y

HOMOZYGOUS ROUND YELLOW



___________ ____________ _____________ _____________R Y R Y R Y R Y

ry ry ry ry

RY

RY

RY

RY

100% of offspring = _______ genotype _______________________ phenotype

RrYyROUND YELLOW

RrYy RrYy RrYy RrYy

RrYy RrYy RrYy RrYy

RrYy RrYy RrYy RrYy

RrYy RrYy RrYy RrYy

R r Y y

HETEROZYGOUSROUND YELLOW



___________ ____________ _____________ _____________R Y r y r Y R y

R r Y y R r Y y



MAKE ANOTHER CROSS

X

POSSIBLE PARENT GAMETES?

RY ry RyrY

RY Ry rY ry

RY

Ry

rY

ry

Sign of a ______________________ cross is a_____________ ratio in offspring.9:3:3:1

____ Round & Yellow

____ Round & green

____ Wrinkled & yellow

____ wrinkled & green

9

3

3

1

RRYY RRYy RrYY RrYy

RRYy RRyy RrYy Rryy

RrYY RrYy rrYY rrYy

RrYy Rryy rrYy rryy

heterozygous dihybrid

__________ratio is a clue that it’s a ____________________________cross

____ ____________ TRAIT 1 ; ____________ TRAIT 2 ____ ____________ TRAIT 1; _____________ TRAIT 2

____ ____________ TRAIT 1; _____________ TRAIT 2

____ ____________ TRAIT 1; _____________ TRAIT 2

9

3

3

1

9:3:3:1

HETEROZYGOUS TWO gene

dominant dominant

dominant recessive

recessive dominant

recessive recessive

PRACTICE MAKING GAMETESfor DIHYBRID CROSSES

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookTOC.html

pure round & pure tall = __________

____ ____ _____ ______



R R T T

R T R T

R T R T

Heterozygous Tall = __________

& pure round

____ ____ _____ ______



T t R R

T R T R

t R t R

Hybrid tall = __________

& pure wrinkled

____ ____ _____ ______



T t r r

T r T r

t rt r

Heterozygous tall = __________

& hybrid round

____ ____ _____ ______



T t R r

T R T r

t rt R

Gene Linkage & Polyploidy10.3

Genetic Recombination

New combination of genes created by _________________ and __________________________

Formula __n = possible gamete combinations

n = number of _________________________

CROSSING OVERINDEPENDENT ASSORTMENT

CHROMOSOME PAIRS

2

Example: peas have 7 chromosome pairs.27 = _____ possible combinations.128 x 128 = __________ possible

combinations after fertilization

Humans have ___ chromosomes

223 x 223 = ____+ trillion after fertilization!

12816,384

23

70

GENE LINKAGE

Genes located ________ to each other on the same chromosome will usually travel ___________ during gamete formation

Exceptions to Mendel’s law of ________________________________.

CLOSE

TOGETHER


Genes A and B (a and b) are close together and are more likely to travel together during gamete formation.

Chromosome Maps

Maps show relative____________ of genes

Crossing over occurs more often between genes that are ______________

Chromosome maps created by using ______________________

POSITIONS

FAR APART

CROSSOVER DATA

Letters show relative position of genes

Crossing over is much more likely to occur between A and ___ than

A and ____

C

B

___________________One or more ____________ of chromosomes

_______________ organisms would be 3n

_____________ in humans and rarely occurs in animals

Sometimes in earthworms and __________________

POLYPLOIDY

EXTRA SETS

LETHAL

GOLDFISH

TRIPLOID

Polyploidy1/3 of all ________________________ are

polyploid

Commercial wheat, commercial oats (6n)

Commercial sugar cane (8n)

Polypoloidy plants often have increased ______ and vigor.

FLOWERING PLANTS

SIZE

TRY THIS! Sample Data for Genes A, B, C, & D.･ Draw a line 1 cm longer than

the greatest crossover frequency making a mark every cm.

･ 1% crossover frequency = 1 cm･ Start with the gene pair farthest

apart and plot their letters on the line. (B and D)

･ Plot genes A and C on your line next. They should be between B and D. ･

Use the crossover frequencies to see how far they are from

each gene (AD = 4%, so A is 4 cm from D)

meiosis and heredity

Education

egg cells

body cells

cells gen

htmle sperm

resulting fertilized

family http

parents sperm eggso

developing embryo