mitosis miosis Flashcards by katie kiley

central dogma

DNA nucleotide sequence to mRNA nucleotide sequence  to amino acid sequence in polypeptide  to phenotype

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central dogma is

the flow of information

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• Hydrogen bonding in DNA is

weak bonding

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Protein is a structural or functional unit that is made up by

multiple polypeptide (insulin is made up with one polypeptide)

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Most proteins are made up of multiple

polypeptides (they can be identical or different)

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o Polypeptides are made up by a sequence of

amino acids

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• Hemoglobin =

approx. 150 globins

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o Two genes responsible for hemoglobin

structure(alpha and beta)

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o Concentration of oxygen and pH can affect

hemoglobin

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o Mutant beta globin has a change in one

nucleotide

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 Abnormal cell shape

cell death and loss

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o Ss genotype

sickle-cell hemoglobin and normal hemoglobin

 Sickling RBC’s only show under very low oxygen conditions

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ss genotype

sickle cell hemoglobin only frequent sickling of RBC’s

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o Pleiotropy –

changed in multiple genes – as a consequence of variations in one gene. One gene influencing many
 Cystic fibrosis is also a pleiotropy

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o Genetic heterogeneity (not heterozygosity)

 When you have something like cystic fibrosis, and looking at a population, the genetic origins may vary. The particular mutated gene, or how it is mutated, is different from one person to the next
 It could be a dominant allele in one family, or a recessive gene in another
 Genetic heterogeneity is the opposite of pleiotropy

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• Production of melanin

is complex

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• Cell cycle consists of two

distinct phases(interphase and m-phase-mitosis or miosis)

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mitosis

growth and maintenance

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meiosis

sexual reproduction

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cell cycle also includes

cytokinesis (usually happen at the same time)

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active gene expression and cell activity  preparation for DNA synthesis

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(not actively dividing – haven’t approached S-phase yet ((neurons)) either terminal differentiation and arrest of cell division  cell remains specialized but does not divide OR eventual cell death (apoptosis)

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S phase

= DNA replication and chromosome duplication

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preparation for cell division

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M-phase

cell division and mitosis (somatic cells) and Meiosis (germ-line cells)

check points

to see if each phase has completed to move onto the next

o Concentrations of each cyclin

rise and fall at unique points in the cell cycle (near check points)

o Other proteins mediate

cyclin synthesis and degradation

〖Kinase〗_CD

cyclin dependent kinase (remain relatively constant) and onlyactivated by binding cyclin

 Kinase uses ATP to

phosphorylate other proteins

enzymatic activity of each kinase_CD

rises and falls during cell cycle

When the activity of each cyclin- kinase_CD peaks, it

activates other proteins that promote specific cellular activities

Cyclin- kinase_CD

operates the same in humans as it does mechanically in something like yeast

• We study chromosomes during

M-phase

• Sister chromatids aren’t always

identical (subtle difference)

Haploid (N)

one copy of genetic material subdivided into chromosomes

Dipliod (2N)

two copies of genetic material subdivided into chromosomes

• Mitotic cells maintain

the diploid number

• Meiotic maintains

haploid number

46 chromosomes

humans

48 chromosomes

chimps

how many types of histones are there

5 (H1, H2a, H2b, H3, H4)

o DNA wraps around the four about 1 ½

super coiling

histones regulate

gene expression

o Multiple stages of super coiling help make up a

nucleosome

chromatin

substance which has approx. equal amounts of DNA and histone proteins

level of super coiling:Euchromatin

= maximum condensation state. |  Less packed and found in interphase

level of super coiling: Heterochromatin

= most compact condensation state |  Found in m-phase (maximum condensation)

level of super coiling: Constitutive

= fully condensed – permanently non-expressed. |  Girls have two X’s which means one is permanently non expressed while one will condense and uncondense regularly

• Mitosis introduces

no genetic variation

mitosis occurs in

cells that maintain the diploid state – somatic cells

germ cells go through

meiosis going drop diploid to haploid

• If you’re a plant

– you go through mitosis (making spores?)

• Kintetochore

– helps pull sister chromatids apart. Spindle fibers will attach during cell division

centriole

made up of microtubules (circular)

s-period of DNA

chromatin is duplicated (euchromatic stage)

mitosis begins shortly after

chromatin condenses and chromosomes appear during prophase

o There is no nucleus during

prophase

o Chromosomes will line up in a single plane in the center of the cell

metaphase

o Each chromosome splits (sister chromatids separate during

anaphase

mitosis ends in

telophase and the cell divides (cytokinesis)

• Separation of chromosomes 

disjunction

meiosis division 1

reduction division. Going from diploid to haploid | o Makes some genetic difference between cells

meiosis division 2

o Cuts chromatids down | o Further adds to genetic diversity

Three Mechanisms by Which Meiosis Generates Genetic Diversity

• Disjunction of chromosomes (splitting of pairs) • Independent alignment of different pairs of homologous chromosomes • There can be recombination through crossing over o Enzymes facilitate the chromosomes crossing over o The process can occur anywhere and it may not happen more than once

• Chiasmata

= points of crossing over

• Prophase One is one of the most

important phases | o Leptotene to zygotene  to pachytene  to diplotene

Leptotene

= chromatid begins to condense and nuclear envelope and nucleolus disintegrate

zygotene

homologs synapse and bivalents seen  chromatin continues to condense

pachytene

= crossing-over tetrads become visible and chromatin continues to condense

diplotene

= synapsis loosens and tetrads and chiasmata are visible – chromatin continues to condense

Dikinesis =

o chiasmata terminalize  maximum condensation of chromatin

plant life cycle

* 2n to 2n sporophyte * Then miosis to 1n spores * Mitosis then gametophyte (1n) and mitosis again to form 1n gametes  fertilization

mendels scientific method

``` • Trait-by-trait analysis o Reductionist approach • Used large samples; quantitative analysis of crosses (interpretation of proportions) • Multigenerational crosses • Hypothetico-deductive reasoning ```

mitosis miosis Flashcards

(74 cards)