cell division:mitosis:genetics Flashcards
describe nature of eukaryotic dna
linear chromosomes that are made up of chromatin. 46(23 types A-W(shapes))
define allele
different versions of the same gene( Af(ather) Am(other) ) ex: E or e
define homologous chromosomes
contain same gene traits( Af(ather) Am(other) )
define ploidy
number of sets of chromosomes in nucleus (ex: haploid-1 set, diploid-2 sets, triploid-3sets, tetraploid-4sets)
define haploid #
numbwr of chromosomes in a complete set
define cell cycle
generation of a cell to division of a cell
what are 3 stages of cell cycle
interphase, mitosis, cytokinesis
what are the three stages of interphase?
Gap(G1)
synthesis(S)
Gap(G2)
what happens during Gap(G1)
growth, normal cell stuff, massive production of enzymes for DNA replication
what happens during synthesis(S)
dna replicated centrials replicate(mtoc) making dyads
what happens during gap(g2)
growth, massive production of tubulin, mitochondria and chloroplast replicate
define dyad
2 sister chromosome held together by a centromere
define sister chromatids
exact copiesof each other
define centromere
contains kinetochore protiens and holds th sister chromatids
What are the 5 phases of mitosis(nuclear division)?
prophase, prometaphase, metaphase, anaphase, telaphase+cytokinesis
what happens during prophase
chromosomes start to condense, centrioles move to opposite ends of cell, centrials produce polar microtubules+aster microtubules
what happens during prometaphase
nuclear envelope disappears, chromosomes finish conducting, centrials produce kinetochore microtubules, then spindle apparatus(p,a,k microtubules)
what happens during metaphase
k microtubules move dyads to center of the cell(metaphasis plate)
what happens durinf anaphase
polar microtubules get longer, centomere break, k microtubules shorten, pulls chromatids to opposite ends of cell
what happens during telephase+cytokinesis
chromatids reach opposite ends + get contained w/i nucleai, spindle apparatus disappear, chromatids decondense actin belt of metaphasic plate constricts to pinch cell in half(cytokinesis)
difference of plant cell division from animal?
the same except no centrials in MTOC, no aster fibers, cytokinesis occurs through cell plate formation
how to get a zygote?
sperm(1N)+egg(1N)—->zygote(2N)
define gametogenesis
the process of producing gametes, or sex cells, from diploid germ cells through cell division, meiosis, and differentiation
meiosis (reduction division) 2 divisions?
Meiosis 1 and Meiosis 2
what happens in meiosis 1
interphase same as mito
prophase1+prometaphase-same as mito
synapsis occurs- homologeous chromosomes line up and h-bond to each other crossing over occurs now-homologs exchange segments so traits now swapped (happens ~50-70 times per meiotic divi)
metaphase 1-23 tetrad line up SAME
anaphase1- homlog sep SAME
telephase+cytokinesis-same as meiosis except chromosomes stay condensed, nuclear envelope does not form, parental sets of chromosomes do not stay tg in first mieotic divi
what happens in meiosis 2
interphase same as mito
prophase 2-same
prometaphase 2- same
metaphase2- same as mito
anaphase 2-same as mito
telephase 2+cytokinesis-same as mito
MITOSIS OF HAPLOID CELLS
define independent assortment
rando. arrangement of homologus pairs at metaphoric plate in metaphase 1
describe spermatogenesis
2N 1° spermatocyte goes through meiosis 1 dyad seperation making two 2° spermatocyte then meiosis 2 occurs and chromatids seperate into 4 1N gamete sperm
describe oogenesis
2N 1° oocyte goes through meiosis 1 turning into 1 BIG 2° 1N oocyte and one 1N polarbody then big oocyte goes through meiosis 2 and breaks into small polarbody and one BIG 1N oocyte (1 gamete)
define error nondisjunction
some or all the chromosomes (dyads) fail to seperate in meiosis 1
what arw the 2 results of error nondisjunction
aneuploidy and polyploidy
define aneuploidy
number of chromosomes is not a whole multiple of the haploid number. ex: cell has 4 homologeous cell go through partial nondisjunction but when breaks one cell has 3 homologeous and other has 1 etc etc
describe polyploidy
2N–complete nondisjunction->2N egg(if right supoosed to be 1N) breaks into 3N sterite if +1N speem added and also breaks into 4N sterite if +2N sperm
define locus
physical location of gene on chromosome
define homozygeous
2 same alleles ex: EE or ee
define heterozygeous
2 diff alleles ex: Ee
define dominant allele
fully expressed allele if present in gene pair ex: E
define recessive allele
allele only expressed in homogeneous state
define genotype
allele made up of gene pair ex:EE,Ee,ee
define phenotype
physical expression of genotype
what are genetics two fields of study?
mendelien genetics- patterns of inheritance
molecular genetics- structure + function of genetic material
describe mendelein genetics and monohybrid crosses
took white flower pea plants self crossed them and got alll white offspring called them true breeders, then took purple flower pea plants self crossed and got some true breeders and some made purple+white offspring, then crossed those true breeders(parental generation) and got F1gen all purple offspring then self crossed those offspring and got F2gen and got some purple(705) and white(214) making a 3:1 ratio
mendelien genetics monohybrid crosses with our knowledge applied
TB purple x TB white
AA. aa
(s) A. a. (e)
F1. Aa
1/2A 1/2a. 1/2A 1/2a
1/4AA, 2/4Aa, 1/4aa
define mendels 1st law(principle of segregation)
organism passes 2 diploid factors(alleles) for each trait ans gamete production results in each gamete getting 1 of these factors
mendelien genetics dihybrid crosses
TB round 🟡 x TB wrinkled green
self cross.
F1 all round yellow
self cross
F2 🟡, 🟢, wri Ye, wri Gre
9.8: 3.4: 3.1: 1
9:3:3:1 ratio
define law of independent assortment
factors for traits are sorted independently of each other during gamete production
describe non mendelien inheritance
what if pea colors and texture on same chromosome(linkage)?
TB RRYY x. TB rryy
RY. ry
F1. RrYy
RY,Ry,rY,ry. RY,Ry,rY,ry
cancel middle two
RRYY,RrYy,rryy
1:2:1 ratio
define incomplete dominance
dominant allele doesmt completely repress/mask recessive allele. ex: 4° flower D-red d-white, DD-red dd-white Dd-pink
define codominance/codominant allele
both alleles fully expressed in heterozygote ex: D-red d-white Dd-red+white
describe human blood types
3 alleles, I^(A)-a protien I^(B)-b protein i-no protien code.
A-I^(A)I^(A), I^(A)i
B-I^(B)I^(B), I^(B)i
AB-I^(A)I^(B)
O-ii
define epistasis
one gene controls the expression of another
example of epistasis?
retriever dog. 2 genes for coat color. pigment gene- B-black b-brown. deposition gene- E-pigment deposited e-not deposited.
EE. Ee. ee
BB,Bb,bb
black. ,brown. yellow
define polygenic trait
many genes effecting 1 trait
define plieotropy
one gene effecting multiple traits ex: sickle cell anemia(recessive mutation of 1 hemoglobin protien) warps RBC to crescent which can clot but also makes resistant to malaria
define sex linked traits
non gender related traits that show a gender related inheritance pattern
what type of chromosomes do humans have related to sex linked traits?
22 sets of homologeous chromosomes (autosomes-chromosomes that arent sex chromosomes ) and 1 set of sex chromosomes
what is the 1 set of sex chromosomes humans have?
x and y
what is the x sex chromosome?
large, contains mostly gender specific genes(M+F) and non gender specific genes
what is the y sex chromosome?
small aprox 70 genes. has SRY gene and other male specific genes
define SRY gene
its epistatic over gender specific genes so if present them male genes expressed, if absent female genes expressed
ex of sex linked trait
color blindness
what are two parts of molecular genetics
DNA(deoxyribonucleic acid) and RNA(ribonucleic acid) both are polymers of nucliotides
what are the two types of nitrogenous bases?
pyrumadines and purines
what three nucleiotide bases applly to pyrumadine? +whether they are for dna or rna
cytosine(dna rna), uracil(rna), and thymine(dna)
what nucleiotide bases apply to purines? +whether theyre dna or rna
adenine(dna rna) and guanine(dna rna)
what nucleiotide bases bond to what on a DNA strand?
A to T
G to C
what two jobs does dna have?
replication and codes for protiens
what is dna replication?
complimentary based pairing(A to T, G to C). chromosomes contain origins of replication(OR)
define origins of replication
short sequence of nucleiotide based pairs that start the process of replication
what molecules are involved in replication?
heliace, topoisomerace, primace, DNA polymerace III, DNA polymerace I, and DNA ligace
what does helicace do in replication?
binds to OR and moves in a 3’->5’ direction, generating the 2 strands
what does topoisomerace do in replication?
binds and moves ahead of the helicace and unwinds/unhelixess DNA strand
what does primace do in replication
attaches free RNA nucleiotides to the DNA nucleiotides at the OR- called a primer
what does DMA polymerace III do in replication
adds free DNA nucleiotides to exposed DNA strand moving 3’->5’
what does DNA polymerace I do in replication
removes RNA nucleiotides and replaces them with DNA nucleiotides
what does DNA ligace do in replication
attaches DNA strands together
how to make the leading strand in DNA replication?
helicace does its job, primace does its job, topoisomerace does its job, DNA polymerace III binds to DNA strand and primer and moves 3’->5’ building new dna strand
how to make the lagging strand in DNA replication
about every 200 bases primace binds to the unreplicated strand and add a primer, dna poly III binda to primer + unreplicated strand and moves 3’->5’ building small segment of DNA(okazaki frag), DNA poly I removes primer+does ita job, then dna ligace does ita job
what are the two steps of protien synthesis
transcription ans translation
define transcription
information on gene is used to build an RNA
define translation
information on RNA is used to build a protein
define promotersite on a transcription?
short sequence of nucleiotides aprox 40 base pairs upstream of gene that contain tata box
define termination site on a transcription
short sequence that identifies the end of a gene
describe the process of transcription
transcription factor(protien) binda to chromosome just upstream of the promotersite, allows RNA polymerace to bind to promotorsite, RNA polymerace moves down gene separating the 2 DNA strands and adding RNA nucleiotides to the 3’->5’ strand, RNA polymerace reaches terminator site + causes RNA polymerace to detach RNA poly to be released(RNA transcript) + DNA strands to connect
what are the three types of RNA?
ribosomal RNA(rRNA), messenger RNA(mRNA), transfer RNA(tRNA)
define ribosomal rna
small piece of RNA that combines with proteins to make ribosomes
define messenger rna
linear strand of RNA that serves as instructions for building a protien. is organized into codons ex: AUG~CCA~TUA etc
define codon
3 nucleiotide sequence on rRNA that codes for a specific amino acid(64 codes 20 amino)
mRNA coding examples and chart
RNA codon=UCU
DNA DNA triplet=AGA
DNA anticodon=AGA
DNA—->RNA
C. - G
G. - C
A. - U
T. - A
define tRNA
folded RNA that carry amino acids to the ribosome to make a protien. anticodon binds to codon
3 steps of translation
initiation, chainelogation, termination
describe initiation
ribosome(rrna) binds to mrna and to initiator trna
describe chainelongation
once the initiation complex formed the next codon is exposed in ribsome ,the next trna(w/amino acid) binds to the codon, peptide bond is formed between the amino acids(linking them) then first trna detaches from AA and exits, ribosome moves down mrna and exposes the next codon, then repeats at next trna
describe termination
ribosome reaches the stop codon(no trna)a releasing factor(protien) binds to a stop codon causing ribosome mrna and protien to seperate
three ways gene amplification(speeding up of translation) occurs
- there may be more than 1 copy of gene on the chromosome
- multiple simultaneous transcription of a gene
- multiple simultaneous translation of the mRNA
define gene
section of chromosome that codes for an RNA
what does coding gene do?
codes for a protien
what does non coding gene do
doesn’t code for a protien
what does polyadenylation do during post transcription modification of mrna
adds adenines to end of mrna(poly A tail)
what does splicing do during post transcription modification of mrna
removes the introns from the mrna to make a functional mrna
define intron(post transcription modification of mrna)
short section of mrna that gets removed
what does alternative splicing do during post transcription modification of mrna
creates unique combination of exons to produce 2 unique protien (don’t have to use all exons)
percentages of DNA?
2% off dna is genes
8% of dna-endogenous retroviral dna
define psuedo genes and example
non functional genes that are remnants from ancestors. GLUD- gene found in mammals- produces enzymes for vitamin C synthesis preventing scurvy
define virus
protien capsul contains genetic material capable of injecting that material into a host cell and making more virus
two types of viruses?
dna virus and retro virus
describe dna virus
inserts dna into host, dna gets transcribed and translated and makes more virus
deacribe retro virus
inserts mrna into host and reverse transcriptase(enzyme) (reverses transcription) dna becomes incorporated into host dna (provirus) this stays dormant but can get triggered +be expressed where it makes more viral particles and kills host
