Cell Division Flashcards
Genome
all the DNA within the cell
Zygote
common ancestor of all human cells
Human somatic (body) cells contain how many chromosomes?
46 chromosomes
-23 copies of paired chromosomes
sex cells only have half the number of chromosomes a body cell would have
Homologous chromosome pairs
are the 2 different copies of the same chromosome in a diploid organism
- one is given by the mother
- one is given by the father
Same size (except X and Y) carries same genes (except X and Y) Genes in same loci (except X and Y) can have different alleles not held together by a centromere
Sister Chromatids
Only exist after DNA replication (100% identical)=Dyads
- same size
- carries same genes
- genes in same loci
- same alleles
- held together by a centromere
Referred as Replicated homologous chromosomes:
-46 replicated homologous chromosomes=23 pairs of homologous chromosomes
Dyads
replicated chromosomes that look like an X
Centromeres
Link sister chromatids together to form a dyad
-also assemble kinetochores
Kinetochores
are proteins that orient themself on either side of a dyad centromere
-attach microtubules to help separate sister chromatids during karyokinesis
Karyokinesis
process where one parent nucleus divides to form two daughter nuclei
Cytokinesis
physical process of cell division
- process that occurs after karyokinesis
- physically separates the cytoplasm and cell membrane
Ploidy
number of chromosome sets four in a cell
Diploid cells
cells that contain two complete sets of chromosomes
Human somatic cells have a diploid number of 46 chromosomes which means each set contains 23 pairs
Haploid cells
have half the number of chromosomal sets as a somatic cell
-uniquely describes gamete cells
Human genets have a haploid number of 23 chromosomes-they contain just one chromosomal set
Gametes
Haploid cells
-contain 23 chromosomes
used by organisms during sexual reproduction
Germ cells
divide by meiosis to form gametes
- diploid
- 46 chromosomes
Cell Cycle
composed of two broad phases
1) Interphase
- 90% of cell cycle, where most cells are found
2) M Phase (Mitosis)
- karyokinesis occurs (division of the replicated DNA and nucleus)
- followed by cytokinesis
Go-Gap Phase 1 (G1) of interphase Sam- Synthesis Phase (S) of interphase Go-Gap Phase 2 (G2) of interphases Make-Mitosis of the M phase Cake- Cytokinesis of the M phase
Gap Phase 1 (G1): of interphase
cell potential grows in preparation of a future division
- cell produces more cytoplasm, proteins, and organelles
- assess conditions if not favorable it will enter G0 phase.
- if conditions are favorable- proceeds to S Phase
Gap Phase 0 (GO) of interphase
cells that will not divide after being made are found here -go about normal function EX: -neuron cells will send action potential -muscle cells will contract NO DIVIDING
Synthesis Phase of Interphase
where a cell will replicate its genome in preparation of an ensuing cell division
-after replication cell enters G2 phase of interphase
Gap Phase 2 (G2) of interphase
cell continues to grow and prepare for division
replicates organelles
checks for:
- accuracy of DNA replication
- Mitosis promoting factor (MPF)
What are the four main phases of Mitosis?
What does a Diploid parent nucleus produce?
2 genetically dental diploid daughter nuclei
Prophase
Metaphase
Anaphase
Telophase
Prophase of Mitosis (M Phase of the cell cycle)
- Chromatin condenses into chromosomes and become more visible
- nucleolus and nuclear envelope begin to disappear
- spindle apparatus beings to form
Metaphase of Mitosis (M phase of the cell cycle)
Spindle apparatus guide chromosomes to the cell equator called the metaphase PLATE
-Dyads lined up in a single fie at the end of meta phase
Anaphase of Mitosis (M phase of the cell cycle)
Shortest step of mitosis
Kinetochore microtubules shorten to pull centromere apart
-sister chromatids now called chromosomes are pulled toward opposite poles
-Polar spindle fibers bigin to elongate the cell
Telophase of Mitosis (M phase of the cell cycle)
Chromosomes arrive at opposite poles and begin to decondense
- nuclear envelope material surround east set of chromosomes
- mitotic spindle breaks down
- spindle fibers continue to push poles apart
Cytokinesis: animal cells
begin in late anaphase by formation of a cleavage furrow
-creates a contractile ring that gets together until it eventually pinches the cell in two
Cytokinesis: Plant cells
begin around telophase
- Golgi apparatus releases vesicle and creating a cell plate
- Cell plate transforms into the middle lamella which cements adjacent plant cells together
What are some mutations that cause a cell to become more cancerous?
mutations in protooncogenes and tumor suppressor genes
Binary Fission
how archaea, bacteria, and mitochondria/chloroplasts (organelles) reproduce
- replicate their genome as cell division is taking place (replication of DNA and division of cell occur at the same time)
- No spindle apparatus
Meiosis
involves same general steps as mitosis
- Meiosis occurs twice (mitosis only occurs once)
- produce a total of 4 haploid daughter cells from one diploid parent
2 parts: Meiosis I-homologous chromosomes are split -reductional division -ploidy of each cell will be halfed Meiosis II-sister chromatids split -looks a lot like mitosis;
Prophase I
chromatin condenses into chromosomes
- nucleolus disappears
- nuclear membrane disassembles
- paring of homologous chromosomes and crossing over occurs which creates genetic diversity
Genetic recombination
occurs when crossover event produces chromosomes that haven’t been seen in either parent
-make genetically diverse offspring
Metaphase I
-bivalents/tetrads line up on metaphase plate duet meiotic spindle apparatus
Anaphase I
separates homologous chromosomes from each other by kinetochore microtubule shortening
- pulled toward opposite poles of the dividing cell
- separates homologous chromosomes; sister chromatids not separated here
Will not start unless one chiasmata Is recognized
Telophase and Cytokinesis I
Telophase I
-meiotic spindle disappears as nuclear envelopes form
Cytokinesis I:
animals-formation of cleavage furrow
plant-formation of cell plate
Prophase II
chromatin condensing into chromosomes
- nucleoli disappearing
- nuclear envolope disintegrating
- meiotic spindle apparatus is formed
Metaphase II
just like metaphase in mitosis
Spindle apparatus guide chromosomes to the cell equator called the metaphase PLATE
- Dyads lined up in a single fie at the end of meta phase
- *each cell will have a haploid number of chromosomes
Anaphase II
pull sister chromatids of each chromosome apart at the centromere
- doubles the number of chromosomes in each cell
- pull chromosomes to opposite poles
Telophase II
reforms a nuclear envelope around each chromosome set
- create two new daughter nuclei
- chromosomes will decondense back into chromatin
- nucleoli will reappear in each nucleu
Cytokinesis II
sepearts each daughter nucleus into two new cells
- produces findal product
- four haploid daughter cells
Chromatin
general packaging of DNA around histone proteins
- helps condense DNA to fit within the nucleus of the celll
- exist in chromosomes during mitosis and meiosis
DNA organization
DNA wraps around proteins called HISTONES forming a complex called nucleosome.
each nucleosome contains 9 histones
Euchromatin
- represents parts of your DNA that consists of “loosely-packed” nucleosomes
- its easier for RNA polymerases to access the DNA code and transcribe our genes
Heterochromatin
represents parts of your DNA that consists of tightly packed nucleosomes
-these areas of DNA tend to be inactive in transcription
DNA helicase
seperates complementary strands at the replication fork
SSB
Single stranded binding proteins
-proteins that prevent two strands from coming together after they seperate
Topoisomerase (DNA gyrase)
relaxes the DNA double helix from the tension that opening the helix created
Primase
Provides a 3’OH group for DNA polymerase to attache nucleotides to
DNA polymerases
class of enzymes that extends DNA in the 5’ to 3’ direction
DNA sliding clamp
Helps hold DNA polymerase to the template strand
DNA ligase
Glues together separate pieces of DNA
Telomerase
Adds repetitive DNA to the ends of eukaryotic chromosomes which prevents critical information from being lost
Operon
a group of of related genes are under the control of one promotor site
Function:
-makes sure the cell conserves its resources unless the resources are required
Lac Operon
HoOperon seen in E. Coli
- ex: inducible operon-usually inactive unless its induced to become active
- induced when glucose is not present but lactose is
Controls 3 genes:
LacZ
LacY
LacA
genes code for proteins that are used in metabolism of lactose
How is the Lac operon controlled
- Lac repressor protein
- encoded by the gene LacL-not apart of lac operon
- constitutively expressed-gene is always being transcribed and translated
- repressor binds to the operator, RNA polymerase will not be able to bind effectively to the DNA and lac genes will be transcribed and translated at low levels
- IN the presence of lactose, allolactose will bind to the lac represser protein, causing a conformational change and cannot bind operator ration - cAMP levels and catabolite activator protein (CAP)
What are the three main types of mutations?
- base substitutions (point mutations)
- Insertion
- Deletion
Point mutations
or called base substitutions
-occur when one nucleotide is replaced by a different nucleotide
3 types:
- Silent
- change in the DNA code result in no change in what amino acid the codon codes for - Missense mutation:
- change in the DNA code results in the codon now coding for a different amino acid
- conservative missense mutation-mutated amino acid has the same properties as the unmated amino acid - Nonsense mutation
- codon is mutated to a stop codon
- protein shorter and can be detrimental to protein function
What happens when a histone protein is acetylated?
Acetylation of histones will remove their positive charge and loosen up the attraction between histones and negatively charged DNA generating euchromatin (Loose DNA)
WHICH INCREASES THE RATE of Transcription
Duplication mutation
piece of DNA is copied then reinserted into DNA
-can cause a frameshift mutation
Translocation mutation
when one sequence of nucleotides is excised and reinserted into the DNA sequence somewhere else
-can cause a frameshift mutation
Inversion mutation
type of mutation where a sequence of DNA is excised and flipped and reinserted back into the DNA
Mismatch Repair
DNA polymerase can’t catch all its mistakes
-cell marks the uncaught errors so they can be replaced with the correct sequence
Nucleotide excision repair
repair mechanism for DNA that has been damage.
-damaged strand is cut out and replaced with the correct sequence based on complementary base pairing
2 life cycles of viruses
Lysogenic cycle
- viral nucleic acid will insert itself into the host’s genome
- beneficial to virus because its nucleic acid will be replicated whenever the hosts DNA is replicated
- virus is dormant and does not harm the host
Lytic cycle
- virus takes over the host’s cells’s machinery and does en up harming the host
- breaking apart host genome and replicating many copied of viral nucleic acid; make viral proteins which can lyse (break apart) the host cell and go infect other cells
HIV
human immunodeficiency virus
- RNA virus/retrovirus-a virus that stores its genetic material as RNA
- carry an enzyme called reverse transcriptase which allows them to convert their RNA into complement DNA (cDNA)
wild type allele
normal allele that is most common in nature
Hemizygous
individuals will only have one copy of an allele instead of two
penetrance
the proportion of individuals who exhibit the phenotype of an allele for a given gene
Complete penetrance
vs
Incomplete penetrance
the trait is expressed in the full population that has the allele
when the trait is only expressed in only part of the popuatonin that has the allele
Expressivity
degree of a certain phenotype
Incomplete dominance inheritance
an intermediate between two phenotypes
Ex: white with red flow producing pink flower
Codominance inheritance
contribution of both alleles will be seen
Ex: Blood typing:
A and B= AB blood
-no blood type is dominant
Epistasis
interaction between genes
-one gene can affect the expression of a different gene
Pleiotropy
-one gene gives many different traits
CYSTIC FIBROSIS
Polygenic inheritance
multiple genes affect one trait with continous variation
-one trait given by many different genes
Law of independent assortment
in meiosis, homologous chromosomes will line up on the metaphase plate independently of one another
-seperation of alleles is totally random
Nondisjunction
the failure of one or more chromosome pairs to separate properly during anaphase
-results in production of daughter cells with the incorrect number of chromosomes
Aneuplooidy
abnormal number of chromosomes in the resulting cells
-caused by nondisjunction
Down syndrome
Trisomy at chromosome 21
- resulting from nondisjunction at chromosome 21
- not fatal
Turners Syndrome
X chromosome monosomy that affects females
-physicial abnormalities and sterility
Klinefelters syndrome
Sex chromosome trisomy in males
XXY sex chromosomes
true breeding organism
homozygous for its traits AA or aa
F1 generation
produced after true breeding parents are crossed
-first generation of offspring
Linked genes
found closure together on the same chromosome
-
haplotype
a group of genes that are located so close to each other on a chromosome that they tend to be inherited together
Sucrose
Glucose + fructose disaccharide
Lactose
Galactoase + glucose disaccharide
Maltose
Glucose + glucose disaccharide
atom
the smallest unit o feather that still retains the chemical properties of the element
Cellulose
structure component in plant cell walls
- B bonded polysaccharide
- linear strands packed rigidly in paralel
Chitin
structural component of fungi cell walls and insect exoskeletons
-beta bonded polysaccharide with nitrogen added to each monomer
RNA world hypothesis
RNA dominated Earth’s primordial soup before there was life
-RNA developed SELF REPLICATING mechanism and later could catalyze reactions such as protein synthesis
Nucleoplasm
cytoplasm of the nucleus
nuclear envelope
is the membrane of the nucleus
- contains 2 phospholipid bilayer (one inner and one outer)
- perinuclear space
nuclear lamina
provide structural support to the nucleus
-regulate cell division and DNA
Nucleolus
dense area responsible for making making rRNA
-produce ribosomal subunits
Ribosomes
not organelles
-small factories that carry out translation
Eukaryotic Ribosomal Subunits
60s and 40s subunits assemble in the nucleoplasm and form the complete ribosome in the cytosol (80s)
Prokaryotic Ribosomal Subunits
50s and 30s assemble in the nucleoid and form complete ribosome in the cytosol 70s
Golgi Apparatus
made up of cisternae (flattened sacs) that modify and package substances
Lysosomes
membrane bound organelles that breakdown substances via hydrolysis taken in through endocytosis
Endomembrane system
group of organelles and membranes that work together to modify, package, and transport proteins and lipids
composed of
Nucleus, smooth and rough ER, Golgi apparatus,, lysosomes, vacuoles, cell membrane
Mitochondria
power house of the celll
-producing ATPfor energy through cellular respiration
Cytoskeleton
provide structure function in the cytoplasm
3 types:
microfilament
intermediate filaments
microtubules
Microfilament
smallest type of cytoskeleton
- composed of double helix of actin filaments
- mainly involved in cell movement
Functions of microfilaments
1 Cyclosis
- Cleavage furrow
- Muscle contraction
Intermediate filaments
middle size type of cytoskeleton
-structural support
Lamins
type of intermediate filament
-helps make up the nuclear lamina
Nuclear lamina
network of fibrous intermediate filaments which support the nucleus
Microtubules
largest type of cytoskeleton
- give structural integrity to cells, cilia and flagella
- hollow tubes with walls made of tubular
Tight junctions
form water-tight seals between cells to ensure substance pass through cells and not between them
desmosomes
provide support against mechanical stress
-connects neighboring cells via intermediate filaments
adherens junctions
similar in structure and function to desmosomes
-connects neighboring cells via actin filament
Gap junctions
allow passage of ions and small molecules between cells
Isotonic solutions
have the same solute concentrations as the cells placed in them
hypertonic solution
have a higher solution concentrraiotn than the cells places in them
- causing water to leave the cell
- cell shrivels
Hypotonic solutions
have a lower solute concentrations than cells place them in, causing water to enter the cell
-cell swells up
Lysis
bursting of the cell when to much water enters via hypotonic solutions
Aerobic Cellular Respiration
-phosphorylate ADP into ATP by breaking down glucose and moving electrons around
Involves four catabolic processes: glycolysis pyruvate manipuations Krebs cycle oxidative phosphoryation
Where does glycolysis take place?
in the cytosol and does not require oxygen–also used in fermentation
net product of glycolysis
2 ATP
2 NADH
Pyruvate Manipulations
pyruvate dehydrogenase is the enzyme
1)Decarboxylation
-pyruvate moves from he cytosol into the mitochondrial matrix
-product one CO2
2)oxidation:
2 C molecule converted to acetyl group
-NAD+ to NADH
3)Acetyl CoA is produced
Krebs Cycle
Occurs in the mitochondrial matrix
-cytosol for prokaryotes
produces NADHx3
GTP
FADH2 linked to electron transport chain
Oxidative phosphorylation
ETC and chemiosmosis(ions moving down electrochemical gradient) work together to produce ATP
4 protein complexes-oxidation reduction (redox) reactions in ETC
- protons are pumped from the mitochondrial matrix to t he inter membrane space forming and electro chemical gradient
- INTERMEMBRANE=highly acidic
What is the final electron acceptor in oxidative phosphorylation?
Oxygen and gets reduced to water
ETC goal
- regenerate electron carriers
- create an electro chemical gradient to power ATP production
Where does the ETC occur in eukaryotes and prokaryotes?
Mitochondrial inner membrane for eukaryotes
Cell membrane-prokaryotes
ATP yield of aerobic cellular respiration?
exergonic; negative delta g
36-38 ATP
Fermentation
anaerobic pathway
- only relies on glycolysis
- convert pyruvate into lactate or ethanol to oxidize NADH back to NAD+; now glycolysis can continue
Cori cycle
used to help convert lactate back into glucose once oxygen is available agin
-transports lactate to liver cells and is oxidized to pyruvate
Obligate Aerobes
only perform aerobic respiration
-neeed the presence of oxygen to survive
obligate anaerobes
only undergo anaerobic respiration or fermentation
-oxygen poisens
Facultative anaerobes
can do:
aerobic respiration
anaerobic respirotn
or fermentation
prefers aerobic respiration, bc it generates more ATP
Microaerophiles
only perform aerobic respiration
-high amounts of oxygen are harmful
Aerotolerant organisms
only undergo anaerobic respiration or fermentation
-oxygen not poisonous to them
Adipocytes
cells that store fats
Proteins
least dersirable energy source (carbohydrates most desirable energy source)
Ammonia
toxic
-must be converted into uric acid or urea
Heterotrophs
must get energy from the food they eat
autotrophs
can make their own food
Photoautotrophs
take light energy and convert it to chemical energy using photosynthesis
Photosynthesis
Creates chemical energy that is transferred through food chains
-reduces atmospheric CO2 and releases O2
Nonspontaneous
-prudcing glucose after an input of solar energy (photon)
Photons of light
-in photosynthesis
used to synthesize sugars (glucose) in photosynthesis
Carbon fixation
process by which inorganic CO2 is converted into an organic molecule
-Photosynthesis takes
Where does the Calvin cycle occur?
Stroma
Where do light dependent reactions of photosynthesis occur?
Thylakoids
Light dependent reactions
use light energy to produce ATP and NADPH for later use I the Calvin cycle
Calvin Cycle
Also known as the light independent reaction
-does not directly use light energy, but can only occur if the light dependent reactions are providing ATP and NADPH
Cell Cycle REgulation
prevents cancerous growth
1) Surface to Volume ration
- cell division occurs when Volume is to large
- decrease in S/V lead to division
2) Genome to volume ratio:
- decrease in G/V leads to division
- when volume is to large for cells to support its limited geneome
Steps of replication
1) initiation
- create origins of replication at A-T rich segments of DNA
2) elongation
- producing new DNA strand use different types of enzymes
3) termination
- replication fork cannot continue, ending DNA replication
Eukaryotic Post-transcriptional modificaiton
conversion of pre-mRNA into processed mRNA
1)5’capping
-protect the mRNA from degradation
2)Polyadenylation of the 3’ end
-prevent degrdation by addition of Poly A tail
3) splicing out introns
-
Start Codon
AUG (Met)
Stop Codons
UAA, UAG, UGA
anticodon
group of three tRNA bases (A, U, G, or C) that base pairs with a codon
Aminoacyl-tRNA
tRNA bound to an amino acid
Aminoacyl-tRNA synthetase
enzyme that attaches an amino acid to a specific tRNA using the energy from ATp
3 methods of horizontal gene transfer in bacteria
1) conjugation
- use pili (cytoplasmic bridge)to copy and transfer a special plasmid known as F plasmid
- F+=bacteria contains an F plasmid
- F-= if bacteria doesn’t contain
2) transformation
- bacteria take up extracellular DNA
- Competent bacteria-can perform transformation
3) Transduction
- viruses transfer bacterial DNA between different bacterial hosts
- occurs when bacteriophage enters the lysogenic cycle
Plasmids
circular DNA pieces that are independent from a bacterias singular circular chromosome
Haploinsufficiency
one of gene is lost or nonfunctional and the remaining copy is not sufficient for normal phenotype
haplosufficiency
when the remaining copy of the gene is SUFFICIENT for a normal phenotype
Proto-oncogenes
genes that can become oncogenes (cancer causing genes) due to gain of function mutations
-cause to much protein to be made or pruductin of an overactive protein
Follow one hit hypothesis
Tumor suppressor genes
genes that become cancerous as a result of loss-of function mutations
-normally need to suppress cancer growth
follow 2 hit hypothesis
HAPLOsufficient
p53
important tumor suppressor gene
Called-Guardian of the cell
-upregulated to prevent cell from becoming cancerous
p21
tumor suppressor gene
-inhibits phosphorylation activity to decrease rampant cell division
Retinoblastoma gene (RB)
tumor suppressor gene
- codes for a retinoblastoma protein
- prevents excessive growth during interphase
Crossing over
creates genetic diversity
-occurs during prophase 1 of meiosis
Karyotyping
observe chromosomes under light microscope during metaphase
Classifying organisms?
King Phillip Came Over For Great Soup Kingdom Phylum Class Order Family Genus Species
6 kingdoms are?
Archaea
- Eubacteria
- Protista
- Fungi
- Animalia
Prokaryotes
Do not have a membrane bound nuclei and organelles
Ex: eubacteria and Archaea
Eubacteria: Gram Positive vs Gram negative
Gram +
- thick peptidoglycan layer in cell wall
- stain dark purple
- no outer membrane
Gram -
- thin layer of peptidoglycan in cell wall
- stain pink
- contain outer membrane
BOTH:
-covered by a capsule
Eubacteria vs Arachea
Both: contain cell walls -70S ribosome -DNA is organized in circular ploasmids (horizontal gene transfer via pilli) -REPRODUCE VINARY FISSiion
Eubacteria:
- cell walls contain peptidoglycan
- ester linkage
- DNA lack introns and histones
Archaea
- cell wall lack peptidoglycan
- ether linkage
- contain introns comes have histones
Eukaryotes
contain membrane bound nuclei and organelles
Ex: protista, fungi, plantae, and animalia
Protistata
unicellular eukaryotic organisms
Fungi
Heterotrophic saprophytes
1) Nonfilamentous (yeast)
- unicellular
- reproduce asexually by budding
- facultative anaerobes
2) filamentous fungi (molds)
- multicellular
- form hyphae
- reproduce sexually
- aerobic
Annelida
Earthworm
Bilateral body symmetry
closed circulatory system
Founder Effect
when a few individuals leave a larger population and settle in a new location
-individuals will have a smaller gene pool than their original population
GENETIC DIVERSITY DECREASED
Miller- Urey experiment on earth main conclusion
Organic molecules could form under the hypothesized conditions of early earth
An individual who is color-blind most likely has some deficiency in which part of the eye?
CONES
