Exam 2

-need for more cells: replace normal wear and tear and senescence (growing old)
-daughter cells need all the heredity information as the “parent” cell
-Growth and Development: get bigger, stronger, faster, etc
-Sexual and asexual production

self renewal and differentiation
-capable of dividing and renewing for long periods of time. Can eventually be any cell.
-unspecialized
-can give rise to specialized cell types

-embryos and some in adults
-human embryonic stem cells: from in vitro fertilizations that were donated with consent
-induced pluripotent stem cells: specialized adult cells that can be “re-programmed” to another function

cardiac muscle cells and brain cells, but new research is challenging this saying they lay dormant for a time, then become "activated"

-chromosome is attached to cell membrane
-DNA in single, circular chromosome replicates
-two chromosomes separate and move apart
-new membrane added
-cleavage in between
-two new daughter cells

-folded, spiraled, compacted to fit within a nucleus
-gene: lengths of DNA that code for a trait.
-locus: geographical location on the chromosome of a gene
-telomere: “end” signal for the chromosome, located at each end
-centromere: chromosome movement. Important for when DNA starts to divide

two identical DNA helices attached at the centromeres

chromosome DNA is replicated (copied)

chromosomes that contain the same genes (not necessarily the exact DNA)

23

46

somatic cells that have pairs of homologous chromosomes = 2n

XX for female, XY for men

half or only one type of each chromosome = 1n

Gametes (sperm and egg) have 1 copy of each pair of chromosomes

one each of 22 chromosomes and either an X or Y chromosome

1n + 1n = 2n

acquires nutrients, grows and differentiates, prepares for division. Cell spends most of its time in interphase.

G1: growth and differentiation
S: DNA synthesis
G2: growth and division prep

-chromosomes condense
-spindle forms
-nucleolus disappears; nuclear membrane dissolves
-kinetochore holds chromosomes to spindle

-kinetochores line up on equator
-nuclear membrane still dissolved
-“Meta = middle”

-sister chromatids separate
-move to poles

-chromosomes de-condense
-nuclear envelope starts to re-form
-spindle disappears

-microfilaments contracts
-each “daughter” cell has 1 nucleus and ½ of the cytoplasm
-back to Interphase

Do it

weat and tear, bigger stronger, faster

everywhere but in gamete-producing organs

-Each daughter cell has 1 member of homologous pair
-Cuts number of chromosomes in half
-Sperm/egg has 23 chromosomes (not 23 pairs)
-Keeps chromosome number constant

-duplicated chromosomes condense
-homologues pair up and cross over
-nuclear envelope disappears
-spindle forms

-paired homologues line up on equator
-kinetochores attach to spindle
-homologues swap some DNA

-homologues separate
-sister chromatids stay together
Moves to opposite poles

-spindle disappears
-cytokinesis follows
-microfilaments contract

-Chromosomes recondense
-nuclear envelope disappears (if it ever reformed)
-spindle reforms and attach to sister chromatids

-chromosomes line up on equator
-attached to spindle by kinetochore

-chromatids separate
-move to opposite poles

-nuclear envelope reforms
-chromosomes de-condense
-microfilaments contract

-4 haploid (n) gametes
-1 member of each pair of homologues

interphaese, prophase, metaphase, anaphase, telophase, cytokinesis

unit of inheritance; some length of DNA that codes for a particular trait. Earlobe shape

the physical location of a gene

different version of the same trait or gene at a specific locus. WHICH earlobe shape

Same allele on both homologous chromosomes: AA, aa

different allele on homologous chromosomes. Hybrid: Aa

2

1

male stamen produce pollen that fertilizes female egg in same plant

male stamen of one plant fertilizes female egg of different plant

Some trait that is inheritied unchanged by all offspring of self-fertilization

white flower (self) x white flower (same self) = all white flower offspring < means true breeder

purple flower (self) x purple flower (same self)=all purple flower offspring

1

pairs of alleles on homologous chromosomes separate during meiosis

physical manifestation of the allel. Smooth and yellow

The genes (SsYY)

genes (alleles) are inherited independently of each other

if genes are on the same chromosome, most likely inherited together, based on location. Think of the process of making cells - mitosis = linked

Heterozygote is intermediate between the homozygotes
Red + white gives pink!

heterozygotes (Aa) are carriers to the next generation and have the condition and homozygotes (AA) have the condition commonly in more severe form

-Huntington’s disease, some polydactyly
-variegate porphyria: inability to synthesize haem (haemoglobin)
-traced back to one individual in S. Africa in 17th century

heterozygotes (Aa) are carriers but no condition

Albinism, sickle-cell anemia

-gene is carried on the sex chromosomes
-much more likely on the X than the Y
-Hemophilia (can’t clot), red-green color blindness, patterned baldness

-phosphate group
-deoxyribose sugar
-nitrogen containing base
-Adenine
-Guanine
-Thymine
-Cytosine
-Some are bigger than others. So double helix can be slightly asymmetrical

-typical "X" pattern of a helix
-repeating subunits

Hydrogen bonds. Very weak connection, but doens't take a lot of energy to break apart. Needs to unzip for RNA to code

A and G

S phase within interphase
Each daughter cell gets a perfect (almost) copy of the parent cell DNA

break the H bonds holding the base pairs together. It is the unzipper

pairs up the exposed bases with new (free), complimentary bases

stitch pieces of replicated DNA together from the lagging strand

1 in every 1000 or 100,000. Amazingly low error rate

single nucleotide base is incorrect or incorrectly changed

repair enzymes replace with wrong base. A single letter is wrong

an extra base(s) inserted into strand

base(s) are incorrectly taken out of the strand

piece(s) of DNA are taken out, turned around, then re-inserted

whole globs of DNA taken off one chromosome and attached to another (between 8 and 22 and 8 and 11, tisomy 21)

DNA>RNA>protein

one gene, one enzyme

-one specific gene codes for one specific enzyme
-most enzymes are proteins, but not all proteins are enzymes
-revised to one specific gene codes for one specific protein

-usually single-stranded instead of double
-ribose sugar instead of deoxyribose sugar
-uracil base instead of thymine

messenger RNA (mRNA)
ribosomal RNA (rRNA)
transfer RNA (tRNA)

-code for amino acid sequence of protein from DNA to ribosome in nucleus
-messengers this to the cytoplasm from the nucleus

-important ingredient (along with other proteins) in making ribosomes
-necessary in attaching to mRNA and translating code to tRNA

-carries (“transfers”) the correct amino acid to ribosome
-uses ATP to attach amino acid to one end
-anticodon bases protrude from other end

code from DNA is transcribed into mRNA
in nucleus
base sequence that is complimentary to DNA strand

UAU GCG

-mRNA code is decoded into tRNA, then translated into amino acid sequence of protein
-occurs in cytoplasm
-tRNA base sequence is complimentary to mRNA base sequence

AUA CGC

Codons

anticodons

-RNA polymerase binds to the beginning of a gene at the promoter region ohn DNA
-double strand unwinds
-initiation, elongation, then terminations

RNA polymerase moves down one strand
template stand: DNA strand the RNA polymerase uses to build a complimentary strand of mRNA

-DNA termination signal causes RNA polymerase to let go
-RNA molecule is released
-DNA then re-winds back into double helix shape
-RNA polymerase will move onto another gene

-DNA is transcribed into mRNA
-more RNA nucleotides to form cap and tail
-prevent degradation in cytoplasm
-introns (“non coding” regions) are cut out
-exons pasted together
-mRNA finished product leaves nucleus

-many possible splicing arrangements = many possible proteins from a single gene
-introns are the groovy place for evolution of new proteins
-exons will change places during splicing
-accidental, non-directive
-result = brand new protein that is either harmfull or beneficial

in cytoplasm
INITIATION
-complex of small ribosomal subunit, a start tRNA, and proteins binds to start of mRNA strand
-large ribosomal subunit binds to small subunit

-each codon of mRNA is paired with anti-codon of tRNA
-bond between tRNA and amino acid is broken
-bond formed with previous amino acid is chain
-amino acid chain builds

-chain continues to build until stop codon
-mRNA and chain are released
-ribosome subunits separate