1
Q
Cell Division in Prokaryotes
A
copy DNA and divide via binary fission, DNA circular (necklace) chromosome
2
Q
Cell Division in Viruses
A
require host to divide, protein coat and nucleic acids
3
Q
Cell Division in Eukaryotes
A
observable during mitosis/meiosis, 3 essential parts (Centromere, Telomere, Origin of Replication), sister chromatids are replicated chromosomes, they are only present during cell division
4
Q
Centromere
A
attachment point for spindle fibers, kinetochore is a protein complex, spindle fibers attach to both centromere and kinetochore
5
Q
Telomere
A
2 per chromosome, protection, degrade with each cell division, like a cap for the ends of the chromatids
6
Q
Origins of Replication
A
start replication
7
Q
Hayflick Limit
A
cells can only divide about 50 times
8
Q
Cell Cycle
A
G1: cell growth, prep proteins for division, checkpoint checks to see if DNA is damaged and to make sure the cell is the correct size
G0: non dividing phase
S: DNA synthesis/replication, chromosome has 2 chromatids
G2: prep cell for Mitosis, checkpoint checks to see if damaged DNA was repaired, cell might stall if it does not pass checkpoint
M Checkpoint: are the spindle fibers formed and attached to chromosome
9
Q
Mitosis Purpose
A
growth, healing, makes 2 daughter cells, genetically the same, IPMAT
10
Q
Ploidy
A
the number of chromosomes per cell (count by the centromeres), number of DNA molecules can double but not the centromeres
11
Q
Centriole
A
forms the mitotic spindle, attaches to kinetochore at the centromere and pulls sister chromatids to opposite sides of the cell
12
Q
Meiosis Stages
A
PMAT1 -> Interkinesis -> PMAT2, makes gametes for reproduction
13
Q
Reduction Division
A
1st division in Meiosis, reduces genetic material per cell
14
Q
Equational Division
A
2nd division in Meiosis, equivalent material per cell
15
Q
2 Terms included in Prophase 1
A
Crossing Over and Tetrads
16
Q
Random Separation of Homologs
A
independent segregation and independent assortment
17
Q
LZPDD
A
- happens during Prophase 1
- Leptotene (chromosomes not formed)
- Zygotene (chromosomes pair up)
- Pachytene (Synaptonemal Complex, chromosomes more defined)
- Diplotene (Chiasmata, Tetrad, crossing over)
- Diakinesis (chromosomes ready)
18
Q
Spermatogenesis
A
germ cell -> spermatogonium -> primary spermatocyte -> secondary spermatocyte -> spermatids -> sperm
19
Q
Oogenesis
A
germ cell -> oogonium -> primary oocyte -> secondary oocyte -> ootid -> egg
20
Q
Parthenogenetic
A
all female, stimulate each other to make complete copies for offspring (virgin birth)
21
Q
Shapes of Chromosomes
A
- described based on centromere location
- Metacentric (centromere in ‘middle’)
- Submetacentric (just slightly off middle)
- Acrocentric (‘high’/away from middle)
- Telocentric (centromere at end of chromosome)
22
Q
Karyotype
A
picture of the chromosome spread in a cell
23
Q
Chromatin
A
eukaryotic DNA that is closely associated with many types of proteins
24
Q
Histones
A
positively charged proteins that attract/wrap negatively charged DNA (can slide up/down DNA molecule depending on charge)
25
Nucleosome
unit of Histone and DNA wrapped around it, around 200 base pairs of DNA
26
Parts of Histone Protein Complex
- 4 core Histones (H2A, H2B, H3, H4), combine in pairs to make octamer protein
- highly conserved (universal)
- Linker DNA (connects nucleosomes, can be transcribed, can be damaged)
27
2 Types of Chromatin
- Euchromatin: 'loose' DNA, relaxed, promoter regions exposed, transcription, can condense (M Phase) and decondense (Interphase)
- Heterochromatin: always tightly packed DNA, centromeres rich in heterochromatin, no transcription, no crossing over
28
2 Types of Heterochromatin
- Constitutive Heterochromatin: areas of chromosome that are always tightly bound (centromeres and telomeres)
- Facultative Heterochromatin: during development an X chromosome is inactivated and turned to heterochromatin (only if organism has 2 or more X chromosomes), reduces 'gene dosage', sometimes too many genes making too much protein is 'toxic' (overdose)
29
Chromosome Puffs
regions of relaxed chromatin (transcription rich regions)
30
mtDNA
mitochondrial DNA, looks like ring, codes tRNA and rRNA, genes for ATP synthesis, maternal inheritance, all your mtDNA is same as your mom, no recombination/crossing over, many copies per cell, many mitochondria per cell
31
cpDNA
chloroplast DNA, looks like ring, genes code for proteins related to photosynthesis
32
Endosymbiotic Theory
anaerobic eukaryotic cell engulfed aerobic bacteria and cyanobacteria, turned into mitochondria and chloroplasts respectively
33
Meier-Gorlin Syndrome
small attached ears, short stature (even in utero), lacking/underdeveloped patella, due to mutation on ORC gene, affects Mitosis
34
2 Types of DNA Synthesis
Theta Replication: DNA replication in prokaryotes, 1 circle becomes 2 (E. coli, mitochondria, chloroplasts)
Linear Replication: DNA replication that occurs in Eukaryotes, multiple origins sites (Autonomic Replication Sites ARSs), ARSs not located in genes but near genes that code for proteins important for replication, line that opens up to create 2 new lines
35
5 Steps of DNA Synthesis
1. Initiation and Unwinding
- Initiator Proteins: bind and phosphodiesteres or ORCs bind to ARSs if in eukaryotes
- DNA Helicase: binds DNA and breaks H-bonds between strands
- SSBs: single stranded binding proteins, keep strands apart, inhibit hybridization and hairpin loops
- DNA Gyrase: topoisomerase enzyme that cuts/fixes strands to relax supercoiled DNA (high torsional strain), binds outside the replication fork
2. Priming
- RNA Primase: adds RNA primers (~10 nucleotides long) complementary to template DNA strand
- DNA Polymerase 3: polymerase that uses 3’ end of primer to extend a new strand with DNA nucleotides (can also correct errors/proofreading)
3. Extension: Continuous and Discontinuous Synthesis
- Leading Strand: DNA added in 5’ -> 3’ direction, needs only one primer, continuous (unbroken)
- Lagging Strand: assembled in Okazaki Fragments, 5’ -> 3’ direction, needs many RNA primers, discontinuous (broken up), due to antiparallel structure of DNA
4. Primer Removal
- DNA Polymerase 1: polymerase removes RNA primer, replaces with DNA, proofreads, leaves a ‘nick’ and cannot bond sugar-phosphate backbone between fragments
5. Ligation of nicks in DNA backbone
- DNA Ligase: enzyme that catalyzes the formation of a phosphodiester bond without adding another nucleotide to the strand
36
Exonuclease
enzyme that can remove one nucleotide at a time from exterior/end of DNA/RNA molecule
37
Meselson and Stahl
1958, using isotope-rich DNA (heavy mass), noticed the mass decreased in a discrete way, proved that DNA undergoes Semiconservative Replication
38
3 Types of Chromosome Alterations
- Rearrangements (duplication, deletion, inversion, translocation)
- Aneuploidy (Euploidy, Nullisomy, Monosomy, Trisomy)
- Polyploidy (diploidy, monoploidy, triploidy, tetraploidy)
39
Fragile X Syndrome
part of the X chromosome breaks off and the genes are deleted, large protruding ears (both), long upper jaw, high-arched palate, double jointed, post pubescent macroorchidism (large testicles), Hypotonia (low muscle tone), 100% penetrance in males, 50% penetrance in females
40
Double Stranded Breaks (DSBs)
- deliberate: meiosis, Prophase 1, Spo11 enzyme, Homologous Directed Repair (HDR) (homolog is template for break, enzymes cross over)
- inadvertent: caused by radiation/toxin, Non-Homologous End Joining (NHEJ) (DNA Ligase joins broken ends, may not always be correct ends due to repeats in DNA sequence)
41
Transposable Elements
DNA sequence self 'cut & paste"
42
Retrotransposons
DNA sequence 'copy & paste' to other areas in genome
43
Nondisjunction
incomplete chromosome segregation during cell division, most consequential in Meiosis, results in nullisomic and disomic gametes, fertilization of abnormal gametes yields aneuploid offspring, can also happen in mitosis for somatic cells
44
Mosaicism
when not all cells in an organism are genetically identical
45
Amniocentesis
process for obtaining genome/karyotype of developing amniote (15-20 weeks), risk of spontaneous abortion
46
Cell Free Fetal DNA (cffDNA)
fetal DNA that circulates freely in the maternal blood, present after 5-7 weeks, can be used to tell sex of fetus, chromosome alterations, indel mutation (insertion/deletion)
47
Autopolyploidy
karyotype consists of more than 2 complete copies of each chromosome of a single species
48
Allopolyploidy
karyotype consists of more than 2 complete copies of each chromosome from multiple species
49
Positive Aspects of Gene Mutation
source of all genetic variation, further provides the raw material for evolution (gene duplication and mutation of Myoglobin -> Hemoglobin)
50
Negative Aspects of Gene Mutation
source of many diseases and disorders
51
Forward Mutation
changing a wild type organism to a mutant phenotype, learn about the function of specific genes (knock-out organisms)
52
Reverse Mutation
changing a mutant into a wild type phenotype
53
Synonymous Substitution
base sub that does not change the amino acid coded by the codon (aka silent mutation)
54
Nonsynonymous Substitution
- base sub that does change codon to a different amino acid (missense mutation)
- or to a stop codon (nonsense mutation)
55
Insertion
addition of one or more nucleotides
56
Deletion
deletion of one or more nucleotides
57
Frameshift Mutation
Insertion or deletion that alters the reading frame of a gene (changing from reading frame +2 to +3)
58
In-Frame Deletion or Insertion
Deletion or insertion of nucleotides in groups of three, this does not alter the reading frame (+3: GCT insert, still +3)
59
Neutral Mutation
changes the amino acid sequence of a protein without altering its ability to function
60
Lethal Mutation
causes premature death
61
Spontaneous Mutagenesis
mutations that occur spontaneously, by chance
62
Induced Mutagenesis
mutations that occur once an organisms DNA is exposed to a mutagen
63
Depurination
purine base snaps off the ribose sugar, polymerase will select a random nucleotide opposite the depurinated base during DNA synthesis
64
Deamination
cytosine loses an amine group to random hydrolysis, forming uracil
65
X-Rays
break the DNA backbone sometimes leading to deletions
66
Thymine Dimers
form under UV light, TT covalent bond, can be interpreted as a single thymine during replication leading to a frameshift on the new DNA strand
67
Oxidation
due to Reactive Oxygen Species (ROS) from cell respiration, can alter bases, ROSs can be counteracted by antioxidants in diet
68
Base Tautomerization
rare form of a molecule with same chemical formula, due to shift in proton position, forms anomalous pairing
69
Strand Slippage
occurs at long, single base repeats, causes indels
70
Intercalating Agents
mutagens that cause indels
71
Germ-Line Mutations
gametes, entire organism carries the mutation, half of your gametes carry the mutation, can be carried to future generations (cystic fibrosis, sickle cell anemia, non-PTC tasting)
72
Somatic Mutations
somatic cells, specific patch of organism is affected, specific organs, tissues, body parts, no gametes carry the mutation (cancer)
73
Life of Bacterium
stuck in corner of the large intestine, need to respond to a variety of temporary situations/environments in order to survive and replicate
74
Lactose
a major carbohydrate found in milk, consists of two 6-carbon sugars linked together
75
Permease
transport protein, allows lactose into cell
76
Beta- Galactosidase
enzyme that breaks down lactose to glucose (preferred food of E. coli)
77
Lac Operon
code for lactose metabolism proteins
78
Operon
cluster of genes that are transcribed together to give a single mRNA, which encodes multiple proteins (contains a promoter and operator)
79
Operator
DNA sequence to which regulator proteins bind
80
Repressor Protein
protein that regulates transcription of the structural genes (“turns off” gene), has 2 binding sites, one for the operator DNA element and one for the inducer
81
Inducer
in the lac operon system is the presence of lactose, “turns on/induces” gene expression by reshaping the repressor protein so it can’t bind to the operator
82
Repression
transcription is off, repressor protein on operator
83
Induction
transcription is on, repressor protein removed
84
lacI- Mutant Repressor
repressor cannot bind to operator, enzymes produced constitutively
85
Mutant Operator (o^c)
nucleotide sequence is changed, repressor cannot recognize and bind to operator, Lac enzymes are synthesized constitutively
86
Operon Gene Regulation
the ability to switch genes on/off allows prokaryotes to respond to a changing environment
87
ecDNA
extrachromosomal DNA
88
Central Dogma
DNA -> RNA -> Protein -> Trait/Phenotype
89
What are the 'in-between' steps of the Central Dogma
- Transcription (between DNA and RNA)
- Post-Transcription (between RNA and Protein)
- Post-Translational Modification (between Protein and Trait/Phenotype)
90
Helix-Turn-Helix (HTH)
transcription factor (TF, increases transcription)
91
Zinc Fingers and Leucine Zipper
TF in eukaryotes
92
Enhancers/Activators
in both prokaryotes and eukaryotes, made of DNA, DNA elements distantly located from the gene, recruits TFs, increases transcription, contrasting elements are insulators and silencers, can be kilo bases away from the gene it affects
93
Response Elements (REs)
DNA that recruits TFs in certain environmental conditions, presence of toxic heavy metals cause TFs to bind to REs, increase gene expression of Metallothionein Gene (protein that transports heavy metals to waste)
94
RNA Interference
small interfering RNA and microRNA bind to complementary mRNA sequence and make a double stranded RNA, ribosome can’t bind, marked for degradation by exosome (protein complex), process occurs in cytoplasm
95
Alternative Splicing
when a single pre-mRNA can be spliced in more than one way to produce different types of mature mRNA
96
Both of the Histone Modifications
Acetylation: strong ionic bonds between Histone and DNA, Histone Acetyltransferase (HAT) attaches Acetyl groups to histone tails, bond strength lowers and gene expression activated, Histone Deacetylase (HDAC) detaches/removes acetyl groups from histone tails
Methylation: Histone Methyltransferase adds a methyl group to histone tail, causes nucleosomes to pack tight, gene expression is deactivated
97
Epigenetics
study of changes in gene expression that occur without change in the DNA sequence, no mutations, Histone modifications and DNA methylation, changes are reversible but also heritable
98
DNA Methylation
- CpG Islands (CPG): target for methylation, abundant in promoter regions
- Demethylaseansferases (Dnmts): add methyl groups at CGIs, methylated DNA is heritable
- Maintenance Methylase: maintains methylations at CGIs
- Demethylase: detaches methyl groups from DNA
99
Effect of DNA and Histone Methylation
deactivates gene expression (not all bad, cells can’t express all genes all the time)
100
Genomic Imprinting
epigenetic changes affect gametes -> affect offspring (aka Transgenerational Effects TGEs)
101
Environmental Factors (Causes) of Epigenetic Effects
diet, pollution, drugs/pharmaceuticals, stress/abuse
Fall of '25 Classes
flashcards
Decks in class (16)
# Cards
-
Zoology Exam 149
-
Botany Exam 150
-
Genetics Exam 153
-
Zoology Lab Practical #117
-
Genetics Exam 2101
-
Zoology Exam 258
-
Botany Exam 274
-
Botany Lab Quiz- Fruits22
-
Zoology Exam 345
-
Botany Quiz- Lichen & Bryophytes12
-
Genetics Exam 339
-
Botany Quiz: Seedless Vascular Plants6
-
Genetics Lab Exam44
-
Botany Final Exam142
-
Zoology Final Exam44
-
Genetics Final Exam85
