Biology 101 Module 4 Study Guide

7/24/2019 Biology 101 Module 4 Study Guide

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Cell theory all organisms composed of one or more cells and that new cells comefrom pre-existing cells

New cells reproduction

Cell division how new cells are made

Two types of cell division in Eukaryotes

Eukaryotes organisms that are not things like bacteria

Mitosis process in which cells produce genetically identical copies of themselves cells needed for growth repair asexual reproduction

Meiosis associated with sexual reproduction number of chromosomes cut in half

Cell division in prokaryotes cell division not complicated as eukaryotes

!rokaryotes prokaryotic "ssion splitting start with a single cell # cells identicalto "rst

$irst step of prokaryotic "ssion make a copy of circular chromosome

# nd step - Cell that has two copies divide in # so each cell has one circularchromosome

%sexual reproduction no genetic exchange with other individuals

Eukaryotic cells have nucleus and organelles

Makes copy of all chromosomes divide up chromosomes each cell gets not onlyright number but right kind of chromosomes

Copy and divide all organelles

&one by mitosis or meiosis

Chromosomes divided up

Cytokinesis comes at end one cell into two cells and divide up content of cell

'ight number and right kind of chromosomes

(aryotype picture of all chromosomes in a cell cells going through mitosis


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)e can see chromosomes only when they begin the process of mitosis when theystart cell division we can only see them in the duplicated condition

$irst thing that happens every chromosome need to make a copy of it

Copy divy up chromosomes among new cells

*nly see already duplicated chromosomes

+ shaped structures chromosomes already duplicated

+ structure already duplicated chromosome

!air #, di erent from each other

!airs based on si.e and shape -

Constriction in middle of chromosome

!airs of chromosomes homologous chromosomes

*ne chromosome from mother one from father

#, rd pair sex chromosomes male big x shape and y smaller thing

%ll other homologous pairs are identical but sex chromosomes are di erent inmales

&iploid number chromosomes found in all the cells in your body

/aploid only found in gamete cells

&iploid number in humans 01 chromosomes #, pairs

/aploid half #, chromosomes

2kin cells in body heart most places 01 chromosomes

*nly "nd haploid only in reproductive cells

Chromosome in unduplicated state long rod shaped thing

Can3t see at this point only see during x shaped structure


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Consists of two sister chromatids identical to each other

4nduplicated rod shape make copy of it

Constriction where duplicated chromosomes are 5oined together

Each half sister chromatid

!lace where they are 5oined together centromere

+ shape structure already duplicated

*ne side chromatid

Two identical they are copies

Chromosome one we can see

2omething that consists of unduplicated thing often refer to as chromosome aswell

(aryotype - #, pairs of chromosomes in duplicated state

(ey thing to remember in mitosis remember what is going on in process

2tart with cell

Chromosome in unduplicated state

Make a copy of it

Chromosome in duplicated state

Copy of every chromosome

&ivy up all copy

Make sure new cells have one each

Mitosis cell cycle single cell for period of time cell divides undergone mitosis

%ll things that happen

67 8nterphrase takes up good portion of cell cyclethings that go on divided up into subphases 9not concerned with speci"cs:&uring interphase when organelles duplicate cell grows in si.e ;uid isadded to insides divide into #Chromosomes duplicate at this pointcell in interphase doesn3t look like things are going on but a lot is going on


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if cell is going through cell division cell expand organelles andchromosomes duplicate longest phase

#7 Mitotic phase with many phases insidea7 !rophase area where nucleus was dark strands chromosomes

nuclear envelope disappears - membrane around nucleus disappears

and chromosomes become visible and spindle "bers form stretchingfrom top to bottom of cell chromosomes attached to spindle "bers transition point to metaphase chromosomes beginning to line up

b7 Metaphase see dark strands lined up along the e


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Nerve cells hardly ever go through cell division

Cancer cells undergo cell division very very rapidly

!rocess of meosis


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Most mammal cells divide only around #>-?> times under conditions before theystop age and die

@imit to lifetime of cells

Cancer cells divide inde"nitely

)hy do cells get out of controlA Number of possibilities mutation most commonreason

Check point genes determines when cell divides or how fre


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'adiation chemotherapy cause mutations in dividing cells

'apidly dividing cancer cells more a ected than normal cells

Cell divides lots of things going on

Chromosomes go into right places

Bery vulnerable time for cells

Chemicals or radiation present may make mistakes when cell is making copy of&N%

Causes cancer cells "ght "re with "re

Dombarded cancer cells su er mutation and can3t function as dividing cells

Dut putting normal cells at risk -

Dut cells that are rapidly dividing - more at risk

/air cells fall out and so on

Malignant melanoma - very serious can go to other places

2kin cancer most fre but you get the cancer around 0>-?>

%ll cells have suicide switch gene responsible for assessing general health of cell

Cripled by mutations

2uicide pulls lever on unhealthy cell and it dies

2kin cancer suicide switch gene gets mutated

Cell without switch continues on duplicating even though it is unhealthy

Main source ultraviolet radiation from sun

%void ultraviolet hard to do

4se sunscreen

,> smoking cause , million worldwide 6- from secondhand

Causes lung cancer

#F of %mericans smoke

#> of high school seniors smoke daily


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Guitting smoking can lower risk of death to that of non smokers 6>-6? years

&amage to lungs not reversible

&on3t recruit new smokers

Meiosis involved in reproduction

2exual or asexual reproduction

2exual involves # parents

* spring combination of genes from each parents

Meiosis comes in

Hametes by each of parents

Hametes come together to form .ygote%sexual reproduction

8nvolves single parent

* spring produced by mitosis identical to parent

Many species do sexual and asexual

2ome species that do exclusevly sexual or exclusivley asexual

8n hydra organism cells that bud o from main body form a brand new littlehydra

Begetative very common in plant

2trawberry plant send out runner new planet let now o spring geneticallyidentical

@ittle runner severed and can be free living

Meiosis sexual reproduction

!roduces gamete cells

Hamete cells haploid

/alf number of chromosomes

/aploid made in one particular part of body by germ cells


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Herm cells found in particular structures of body called gonands - testies 9males:or ovaries 9females: of animals

Hamete producing cells haploid structures of plants

$lowering plant ovary at base of ;ower

Main 5ob of meiosis produce haploid cells

/ave half number of chromosomes as original cell

Not 5ust randomly half of chromosomes

Each gamete one representative of each homologous pair of chromosome

#, pairs one representative from each pair #, pairs of homologous chromosomesgamete has one of two doesn3t matter which one but one and only one

!urpose half number of chromosome of original cell

%nd have gametes of original cell

2exual reproduction 5oining genetic information

Make sure we maintain constant amount of genetic information from generation togeneration

)hat happens in mitosis

67 &uplicate chromosomes

#7 /omoloogus pairs line up 9synapsis:,7 2eparate homologues meiosis 607 2eparate chromatids meiosis #

2ee with evolutionary kinds of things not most eIcient evolution takespreexisting systems modi"es to produce new kinds of things

2ame phases in mitosis di erent things are happening at di erent times

Meiosis 6 -

67 !rophase homologous chromosomes pair up we call that synapsis

coming together#7 Metaphase pair of homologues line up on e


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Must be separated in meiosis 88

Meiosis 88 like miosis 6 but no duplication event already duplicated eachchromosome on e


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2ee how it can happen by considering one of things that occurs independentassortment

Chromosomes - x

!airs of homologous chromosomes two pairs of x3s

2ister chromatids not x3s

Move to opposite poles of cell

8ndependent assortment one representative of each pair of homologues chosen atrandom

!ossible combinations

1 chromoses 9, pairs: # to the power of J

/umans #, pairs # to the #, power J million

'eshuKes genetic material

Crossing over occurs while homologues are in synapsis -

E


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Each chromosome is duplicated

Two x shaped structures- duplicated condition

8n meiosis 6

!air up on e


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Each ;ower color gene has a purple version 9purple allele: and a white version9white allele:

$or any gene an individual has two alleles one fromeach parent

*ne allele from each homologous chromosome

)hat happens when # alleles in an individual are di erent

)hen one allele is for purple ;ower color and other allele white verison

$or some genes one allele is dominant and the other is recessive

Means that an individual with # di erent alleles only the dominant allele will show

This means only way to see recessive trait in o srping both alleles are recesive

&ominant = recessive

$lower color

!urple dominant white recessive

8f plant has one puple allele and one white allele color will be purple

*nly when both alleles are white will the ;ower color be white

@aw of segregatin # alleles for each gene segregation during gamete formation

8f an individual has one allele for purple and one for white ?> of their gametes willhave a white allele and ?> a purple allele

Hene unit of heredity

Hene locus place on one chromosome where gene is located

%llele form of a gene 9white or purple:

!henotype what the individual looks like

Henotype what the individuals # alleles are


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/omo.ygote both alleles are same

/etero.ygote # alleles are di erent

! generation parent generation

$6 generation 6 st generation of o spring

$# # nd generation of o spring

Monohybrid corss involving one trait ;ower color

&ihybrid corss involving # traits at same time

4sing punnet s


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Not all traits have a simple dominant=recessive nature

8ncomplete dominance -

/etero.ygote intermediate instead of being like the dominant allele

hetero.ygote intermediate

2napdragon ;ower color

'ed crossed with white gives pink

!ink crossed with pink gives red pink and white

'ed snapdragon with white snapdragon like mendells cross purple ;owers andwhite ;ower peas

Mendel got purple ;owered plants all like dominant phenotype

8n snapdragon red with white ;ower get pink ;owered plants

*ne of things we mentioned that mendel was able to do

2how that the prevailing notion about inheritance blended together incorrect

Dlending didn3t occur

This case blending might happen

Not correct phenotype is blend of two

/aven3t lost white allele

!ink ;ower crossed with each other

Het red and white colors back although some individuals that are pink

Closer look

Notatiuon di erent

&on3t have dominance recesive situation

4se letter C for color gene

2uperscript red allele or white allele


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Codominance -

8n hetero.ygotes both alleles expressed

%D* blood group gene

, alleles possible

% and D are codominant

* allele is recessive to % and D

%* %% type %

D* DD type D

** type *

%D type %D

8nteraction between genes

Traits determined by # or more genes

/air color by mammals

# gene responsible for melanin production

% second gene responsible for deposition of melanin in hair

% third gene is also involved when it is recessive the individual is an albino

Melanin pigment

!olygenic inheritance

!olygenic traits

Traits that are combined e ects of many genes

%dditive e ects human skin color

%lleles at several gene loci contribute to the amount of melinin in skin


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!olygenetic traits show continuous variation white skin to very dark skin

'ather than either or

!leiotroppy a single gene may a ect more than one characteristic

The gene responsible for the coloration pattern of siamese cats is also responsiblefor the crossed eyes of siamese cats

Environmental e ct on a single gene trait some cases not 5ust genes thatdetermine trait but environment has e ect as well

2iamese cats or rabbit fur color

Expression of coloration in siamese cat or rabbit is determined by the environment

'abbit dark nose dark ears dark paws dark tail

Not di erent genes in each of these

2ame coloration genes are there

Those genes a ected by temperature of cells that those genes are found in

$or example body of animal such as rabbit

Tend to be warmer than extremeties

!aws ears nose tail cooler

These genes operating in cool cells instead of making white they make dark

Hene expression determined by temperature

Many traits in;uenced by environment

!olygenitc traits

/uman height weight 8G are determined by a number of genes

%ll of these also a ected by the environmen

/uman height -

Henetic component but also environmental component


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&oesn3t get suIcient nutritien stunted in growth potential genes have for height

)eight polygenic trait environment have signi"cat e ect on weght

% ect our overall weight

8G another environment a ect outcome

Nutritionally straved or starved for metntal challenges

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Biology 101 Module 4 Study Guide