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What is the cell cycle?
series of events that cells go through as they grow and divide
What are the phases of the cell cycle?
interphase, prophase, metaphase, anaphase, telophase, cytokinesis
What is the longest phase of the cell cycle?
Interphase
Why is mitosis important?
Used for growth and repair of damaged cells
What are spindle fibers?
form a protein structure that divides the genetic material in a cell
What happens in interphase?
G1- cell size increase S- DNA replication G2- prepare fro cell division (Nucleolus fades, chromosomes not visible, organization phase)
What happens in prophase?
Chromosomes condense Nuclear membrane disintegrates Centrioles move to opposite poles Spindle apparatus formed by microtubules
What happens in metaphase?
Chromosomes line up in the middle of the cell and spindle fibers connect the centromeres to the poles.
What happens in anaphase?
Sister chromatids split and move to either pole (Disjunction)
What happens in telophase?
Nuclear membranes start to form, chromosomes turn into tangle of chromatin, and the spindle fibers fall apart, nucleolus visible, cell plate completed
What happens in cytokinesis?
division of the cytoplasm and creation of cell plate dividing the two cells
What makes the cell cycle different for plants and animals?
Plants- shape doesn't changed and is simply split as you might split a square Animal- shape changes and is split how you might split a drop of water
In what phase do sister chromatids separate?
anaphase
In what phase do the chromosomes become invisible again?
Interphase
In what phase is cytokinesis completed(before next cycle)?
telophase
What phase are daughter cells in as a result of mitosis?
Cytokinesis
What is the name of the structure that connects the two chromatids?
Centromere
In a chromosome pair connected by a centromere, what is each individual chromosome called?
Chromatid
In what phase of mitosis is the last chromatids are together for?
Metaphase
What structure is produced when protein fibers radiate from centrioles?
Spindle fibers
What forms across the center of a cell near the end of telophase?
Cell plate
How does a cell know when to stop dividing?
When the telomeres shorten to a certain length
Control of the Cell Cycle
-Highly regulated -Built in-protein controls check-points Ex. DNA must replicate before division -Allows the cell to pause briefly to check for repairs+errors
What factors influence Mitosis?
Crowding- cause slow or halt in mitosis Chemical signal outside and inside the cell
What do the signals from the outside of the cell say?
Hormones and growth factors in glands transport other parts so the body. Ex.hormones into the brain to signal the uterus to prepare for pregnancy
What do the signals from the inside of the cell say?
Cyclin and Kinesas(2 types of proteins) interact in the cell to activate genes whose products carry out mitosis. Ex. interphase cyclin levels increases towards the end of interphase. Certain # of cyclin and Kinase pairs turn on genes that trigger mitosis. At start enzymes degrade cyclin, process restarts and builds up together.
What is a centriole?
structure in an animal cell that helps to organize cell division
What is a centromere?
The centromere holds the sister chromatids together (made of protein)
What is a chromosome?
A coiled up piece of DNA that has genes that code for traits.(condensed chromatin+ organizes genes)
What is a chromatid?
one half of a duplicated chromosome
What is metastasize?
The spread of cancer throughout the body
Why is cell division important?
Growth from zygote---> adult Repairs damages in body Prevents info overload
What is apoptosis?
programmed cell death
What is p53?
a tumor suppressor gene whose mutant form is believed responsible for many cancers
What tells a cell to stop dividing?
Telomeres that work as a cellular clock Found at end of chromosome
Which stage of cell division are the most cells in?
Inter phase
What are tumor suppressor genes?
genes that normally prevent cell division
What are the 3 buckets in which scientists categorize genes?
Cell fate, Cell survival and Genome maintenance
What are proto-oncogenes?
Proto-oncogenes are a group of genes that cause normal cells to become cancerous when they are mutated. Initiate cell division
If a cell can't move enough material to its center the ratio of its surface area to volume is?
Too small
What are the 3 major stages of the Cell Cycle?
interphase- G1,S,G2 mitosis- PMAT cytokinesis- 1 cell turns to 2
What factors affect mitosis?
Crowding- slow or halt mitosis Chemical signal outside and inside the cell
What are cyclin and kinesas?
Proteins that interact inside the cell to activate genes whose product carries out mitosis
What is an oncogene?
cancer causing gene
What are stem cells?
unspecialized cells from which differentiated cells develop
Totipotent Cells
Before 3 days Zygote -> Morula Can differentiate into any type of cell.
Pluripotent Cells
3-14 days Pre Placenta forms Can differentiate into most types of cells (Embryonic cells can become anything except placenta)
Multipotent Cells
After 14 days Tissue layers form of embryo Can differentiate into a limited range of cell types
What happens in Meiosis?
The same phases as mitosis but it happens twice. The result is four daughter cells.
What forms from meiosis?
four gametes each with only a single set of chromosomes in it
How many chromosomes do gametes have?
23 chromosomes- Haploids
What are some defining qualities of homologous human chromosomes?
Same length Same centromere position, carry genes that control same inherited traits
What happens in Meiosis 1?
Genetic info is exchanged between homologous chromosomes
What is crossing over and why is it important?
the exchange of genetic material between homologous chromosomes, allows for genetic variation
What makes Meiosis 1 and 2 different?
Meiosis 1- 2 sets of chromosomes (Metaphase), crossover, 2 daughter cells, interphase Meiosis 2- no interphase, 1 set of chromosomes (Metaphase), gametes, no interphase
How do gametes contribute to the number of chromosomes in a human?
Gametes are haploid and when sperm and egg are put together it creates diploid which is the ending amount.
In what phase does gene crossing over occur?
Prophase
Where does meiosis occur?
ovaries and testes
What is a chiasmata?
The point where chromosomes crossover.
What is a tetrad?
A pair of homologous chromosomes or a group of 4 sister chromatids during Prophase I.
What is nondisjunction?
Failure for chromosomes to separate properly. Causes imbalance of chromosomes
What are the advantages and disadvantages of Embryonic stem cells?
Advantages: Unlimited self renewal, enhanced telomerase activity Disadvantages: Controversial, teratoma formation, animal pathogens, Immune response
What are the advantages and disadvantages of Adult stem cells?
Advantages: Many sources, not controversial, Immune Disadvantages: Differentiation capacity, self renewal, rarity among somatic cells.
Why are stem cells important?
Study organisms, test different substances, get better understanding of our genetic machinery, regenerate tissues/organs, learn how to repair cell damage
What is the difference between dominant and recessive?
Dominant is always expressed when present. Recessive is only expressed when no dominant genes are present
What is genotype and phenotype?
Genotype - Gene combination for a trait: TT, Tt or tt
Phenotype - Physical appearance of trait: Tall or short
What is a Punnett square used for?
The Punnett square is used to predict what the genotypes/phenotypes will be of the offspring when given the genotypes of the parents.
What is codominance? Give an example.
Both alleles are expressed at the same time without blending; Ex. A spotted flower with both colors of its' parents
What is incomplete dominance? Give an example.
A blending of traits. Ex. Red+White=Pink.
What is a polygenic trait? Give an example.
Trait controlled by two or more genes Ex. Skin color, eye color, cancer, schizophrenia
What are multiple alleles? Give an example.
It is when genes have three or more alleles. Ex. Blood type
What are pedigrees?
A chart or "family tree" that tracks which members of a family have a particular trait
How does the environment affect genes?
The environment can affect a genes expression and influence genetically determined traits. An individuals actual phenotype is determined by its environment as well as its genes. Ex. diet and exercise
What are Mendel's Laws?
Law of Dominance
Law of Segregation
Law of Independent Assortment
What is the law of dominance?
The dominant alleles mask the recessive
What is the law of segregation?
When sperm and egg unite at fertilization, each contributes its allele, restoring the paired condition in the offspring.
What is the law of independent assortment?
Genes for different traits are inherited independently of each other
What is the difference between an autosome and a sex-linked chromosome?
There's 22 pairs of autosomes and only 1 pair of sex linked chromosomes.
What is probability?
likelihood that a particular event will occur
What is homozygous?
Both alleles are the same type
What is an allele?
Different forms of a gene
What is heterozygous?
Organisms have two different alleles for a particular trait.
What is a karyotype?
A picture of every pair of homologous chromosomes within a cell, organized according to size and shape
What are homologous chromosomes?
Two chromosomes with the same set of genes, in the same sequence, sometimes with different alleles
What are autosomal chromosomes?
22 pairs of chromosomes that are coded for characteristics that are NOT sex related
Who was Gregor Mendel?
Gregor Mendel was an Austrian monk and plant breeder.
What is a trait?
a specific characteristic
What is genetics?
The scientific study of heredity
What is heredity?
Passing of traits from parents to offspring
During what process do genes seperate to form gametes?
Meiosis
What are sex-linked traits?
Genes that are located on the sex chromosomes (x) that are not related to sex determination.
Ex: color blindness and hemophilia
What is epistasis? Give an example.
Epistasis - the interaction between two or more genes to control a single phenotype, For example, the gene causing albinism would hide the gene controlling color of a person's hair
What are Rh factors?
Rh Factor is a group of RBC antigens that is present in Rh+ blood and absent in Rh- blood
How is Phenylketonuria and Cystic Fibrosis inherited?
Through recessiveness
How is Huntington's disease inherited?
it is autosomal dominant
How is down syndrome caused?
by the presence of an extra chromosome or by missing one
How is Klinefelters syndrome transmitted?
An additional X chromosome occurring.
What did Griffith do?
The heat killed bacteria was mixed with live harmless bacteria, but it still killed the mouse because of transformation
What did Avery do?
Avery provided more evidence that the transforming material in Griffith's experiment is DNA
What did Hershey and Chase do?
Determined that DNA was the genetic material.
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