Meiosis, cell cycle, mendel and non mendelian, chromosomal Flashcards
(127 cards)
1
Q
What is the cell cycle
A
The life of a cell from its formation until it divides
allows for reproduction of cells, growth of cells, and tissue repair
2
Q
What is the importance of the organization of DNA
A
cells must organize and package their DNA before division
3
Q
Where is DNA organized
A
DNA associates with and wraps around protein known as histones to form nucleosomes
4
Q
What does nucleosomes form
A
Chromatin
5
Q
How does chromatin density change during cell division
A
When a cell is not actively dividing, chromatin is non-condensed form
After DNA replication, chromatin condenses to form a chromosome
6
Q
Why are chromosomes densely packed
A
Chromosomes are densely packed to allow easier division
7
Q
When DNA is replicated what happens to chromosomes
A
It is duplicated
8
Q
What is the og chromosome and duplicated chromosome called
A
Sister chromatids
9
Q
What is the centrosome
A
region of sister chromatid where they are most closely attached
10
Q
what is kinetochore
A
protein attached to the centrosome that link each sister chromatid to mitotic spindle
11
Q
What is a genome
A
all of the cells genetic information
12
Q
What are prokaryotes
A
singular, circular DNA
13
Q
What are eukaryotes
A
one or more linear chromosomes
Every eukaryotes have one specific number of chromosomes
Ex: Humans: 46, Chimps: 48, Elephants: 56
14
Q
What are somatic cells
A
Body cells
Diploid (2n)
Divides by mitosis
Ex: Humans- 2n=46 (23 mom/23 dad)
15
Q
What is a diploid
A
2 sets of chromosomes, one set from each parent
16
Q
What are gametes
A
reproductive cells (egg/sperm)
Haploid (n)
Divide by meiosis
Ex: Humans- n=23
17
Q
What is a haploid
A
one set of chromosomes
18
Q
What are the phases of the cell cycle
A
Interphase (alternation), mitosis, cytokinesis
19
Q
What is interphase
A
Longest protein of the cell cycle
1. G phase
2. S phase
3. G2 phase
20
Q
What is G phase in interphase
A
First phase
Cell grows and carries out normal function
21
Q
What is S phase in interphase
A
Synthesis phase
DNA replication and chromosome duplication occurs
22
Q
What is G2 phase in interphase
A
Second gap phase
final growth and preparation for mitosis
23
Q
What is M phase
A
Mitosis
Cytokinesis
Results in 2 identical diploid daughter cells
24
Q
What is mitosis
A
nucleus divides
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What is cytokinesis
cytoplasm divides
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What are the 5 stages of mitosis
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase/Cytokinesis
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What happens during prophase
Chromatin condenses
nucleoli disappears
duplicated chromosomes appear as sister chromatids
mitotic spindle begins to form
Centrosome moves away from each other
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What happens during prometaphase
Nuclear envelope fragments
Microtubules enter nuclear area and some attach to kinetochores
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What happens during metaphase
centrosomes are at opposite poles
chromosomes line up at metaphase plate
microtubules are attached to each kinetochore
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What happens during anaphase
sister chromatids separate and move to opposite ends of cell due to the microtubule shortening
cell elongates
31
Define telophase and cytokinesis
Two daughter nuclei form
Nucleoli reappear
Chromosomes become less condensed
Cytokinesis occurs
32
What is different between plants and animals during cytokinesis
Animals: a cleavage furrow appears due to a contractile ring of actin filaments
Plants: vesicles produced by the Golgi travel to the middle of the cell and form a cell plate
33
What is "regulation of the cell cycle"
throughout the cell there are chromosomes
- Control points that regulate the cell cycle
- cell receives stop and go signals
34
What are the major checkpoints of regulation
1.G1
2.G0
3. G2
4. M (spindle)
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What happens at the G1 checkpoint
most important checkpoint
checks for cell size, growth factors, and DNA damage
Stop: cell enter non-dividing state known as G0
Go: cell completes whole cycle
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What happens during G0 checkpoint
Some cells stay in G0 forever (muscle/nerve cells)
Some cells can be called back into cell cycle
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What happens during G2 checkpoint
Checks for completion of DNA replication and DNA damage
Stop: cell cycle stops and cell will attempt to repair damage
- if damage cannot be repaired the cell will undergo apoptosis (programmed cell death)
Go: cell proceeds to mitosis
38
What happens at M (spindle) checkpoint
Checks for microtubule attachment to chromosomes at kinetochores at metaphase
Stop: cell will pause mitosis at allow for spindles to finish attaching to chromosomes
Go: cell proceeds to complete mitosis and anaphase
39
What are internal cell cycle regulators
regulation of the cell cycle involves internal control system
1. Cyclins
2. Enzymes
40
What are cyclins
Proteins
synthesized and degraded at specific stages of the cell cycle
concentration varies
41
What are enzymes (in cell regulation)
Known as cyclin-dependent kinases (CDK)
active only when its specific cyclin is present and has specific regulatory effect
concentration remains constant throughout each phase of the cell cycle
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What are external cell cycle regulators
growth factors
contact (density) inhibition
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What is the growth factor of external cell cycle regulators
hormones released by cells that stimulate cell growth
-signal transduction pathway is initiated
- CDK are activated leading to progression through cell cycle
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What is contact inhibition of external cell cycle regulators
cell surface receptors recognize contact with other cells
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What is cancer and how does a cell become cancerous
evasion of the cell cycle
normal cells become cancerous through DNA mutations
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What are DNA mutations
changes in the DNA
Cancer cells have on average accumulated 60 or more mutations on genes that regulate cell growth
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What are Cancer cell traits compared to a normal cells traits
Do not follow checkpoints
divide infinitely
(considered immortal)
Evade cell death and continue dividing even with errors
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If cancer cells infinitely divide and grow, what can this lead to
Tumor
49
What is a tumor and what are the types of tumors
Mass of tissue formed by abnormal cells
Benign tumor: cells are abnormal, but considered to be cancerous
- stay at site and are unable to spread anywhere else
Malignant tumor: mass of cancerous cell that lose their anchorage dependency that can leave tumor site
- metastasis
50
What are genetics
study of hereditary and heredity variation
51
What is heredity
transmission of traits from one generation to the next
Passed from parent to offspring through genes
52
How does offspring inherit genes
segments of DNA code from base units of heredity
offspring acquire genes from parents by inheriting chromosome
53
What is asexual reproduction
single individual
no fusion of gametes
clones
mutations are only source of variation
produce asexually through mitosis
54
What is a clone
offspring are exact copies of parent
55
What is sexual reprduction
2 parents (male/female)
offspring are unique combinations of genes from parents
genetically varied
56
What is a homologous chromosomes
A pair of chromosomes (same size, length, centromere position) that carry same genetic information
- one inherited from mom and 1 from dad
57
What are karotypes
Display of chromosome pairs ordered by size and length
58
What are the 2 types of chromosomes
autosomes
sex chromosomes
59
What are autosomes
chromosomes that do not determine sex
Ex: humans have 22 pairs
60
What are sex chromosomes
determines sex
Ex: humans= X or Y
(22+X or 22+Y)
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What is the life cycle
sequence of stages in reproductive history of an organism from conception to its own reproduction
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What are the two phases in the life cycle
Fertilization and meiosis alternate in sexual life cycle
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What is fertilization
a sperm cell fuses with an egg to form a zygote
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What is meiosis
process that creates haploid gamete cells in sexually reproducing diploid organisms
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What is the result of meiosis
daughter cells with 1/2 the number of chromosome as the parent cell
Ex: Humans
- diploid= 46
- meiosis produces haploids that are n=23 (sperm/egg)
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How many rounds of division are in meiosis
Meiosis 1 and 2
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What are the key events of meiosis 1
1. Prophase 1
2. Metaphase 1
3. Anaphase 1
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What happens in interphase of meiosis 1
Cell goes through G1, S, G2
- DNA copied
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What happens in prophase 1
Synapsis
crossing over (recombination) occurs in chiasmata in DNA (exchanged between pairs)
Every chromatin that is produced has unique DNA
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What is synapsis
homologous chromosomes pair up with each other forming tetrad
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What happens in metaphase of meiosis 1
Independent orientation
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What is independent orientation
tetrads line up at metaphase plate
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What happens in anaphase of meiosis 1
Pairs of homologous chromosomes separate
- sister chromatids are still attached
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What happens during telophase/cytokinesis of meiosis 1
Nuclei and cytoplasm divide
There is now a haploid set of chromosomes in each daughter cell
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What happens in prophase of meiosis 2
No crossing over
spindle forms
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What happens in metaphase of meiosis 2
chromosomes line up at the metaphase plate
Because of crossing over in meiosis 1, chromatids are unique
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What happens in anaphase of meiosis 2
Sister chromatids separate and move towards opposite poles
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What happens in telophase/cytokinesis of meiosis 2
4 haploid cells
reappear nuclei
each daughter cell is genetically unique
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How does meiosis lead to genetic variation
1. crossing over
- produces recombinant chromosomes: exchange material
2. independent assortment of chromosomes
- randomly oriented along metaphase plate during metaphase 1
3. random fertilization
- any sperm can fertilize any egg
80
Who was Gregor mendel
born in 1822
studied math, science, statistics
was a austrian monk
discovered basic principles of heredity
known as "father of modern genetics"
81
What did Mendel experiment on
pea plants
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why did Mendel experiment on pea plants
many varieties
many traits to manipulate
they reproduce sexually, so he could control mating
relatively short generation time
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What types of characteristics did Mendel track
characteristics that come in 2 distinct forms
Ex: seed shape or color
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What technique did mendel use to control his experiments
true breeding
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what is true breeding
organisms that produce offspring of the same variety over many generations of sex pollination
Ex: true breeding with purple plants will only reproduce with purple offspring
86
Define P generation
true-breeding parental gen
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define F1 generation
hybrid offspring of P generation
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define F2 generation
offspring of F1 generation
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What are testcrosses
they help determine is the dominant trait is homo or hetero
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What did mendel discover
mendel noticed that the cross between purple and purple F1 offspring
- white pea chroscteristics comes back in F2
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How did mendel find the dominant trait and resessive trait
Mendel hypothesized that the purple flower must be a dominant trait to the white flower, which is recessive
Mendel performed the same crosses for each of the 7 characteristics of pea plants and found the same results
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what ratio willl F2 get always have when P get is homo and homo
3:1
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How does mendel explain the 3:1 ratio
He created a concept with 4 concepts
1. alternative versions of genes account ofr variations in inherited traits
2. For each character, an organism inherits 2 copies of a gene (mom/dad)
3. if 2 alleles at a locus differ then dominant has no noticeable effect
2. law of segregation
94
what is law of segregation
each gamete for P gen will contain one allele for flower color
-True breeding will have 2 identical
F1 are all hybrid
F2 gen produces 3:1
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What are alleles
alternative versions of a gene
96
What are monohybrid crosses
law of seg was determined by doing crosses between true-breeding plants which produced F1 hybrids known as monohybrids
Ex: BBxbb produce F1 that are all Bb
monohybrid cross would be a cross between F1 hybrid Bb
97
What is law of independent assortment
menders second principle Is law of independent assortment
genes for one trait not inherited with gene of another trait
Ex: pod color Is seperate from pod shape
this law only applies to genes that one located on different chromosomes or very far apart on same chromosome
98
What is a dyhibrid cross
law of independent assortment determined by doing crosses between plants, produced F1 hybrids known as dyhibruds
99
What is the law of probability
la of seg and law of independentt assortment reflect this law
Multiplication rule
Addition rule
100
What is the multiply rule
probability that 2 or more independent events will occur together in some specific combination
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what is add rule
probability that 2 or more mutually exclusive events will occur
Ex: chance of rolling a dice on 1 or 6, 1/6+1/6=1/3
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What are pedigrees
family trees that give visual of inheritance patterns of articular traits
if a trait in dominant, one parent must have it (does not skip gen)
If trait is x-linked, then males are more commonly effected
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What are traits that do not follow Mendel's law
varying degree of dominance]
many traits are produced through multiple genes acting together
some traits are determined by genes on sex chromosome
some genes are adjacent or close to one another on same chromosome and will segregate
104
What are degrees of dominance
Alleles can show varying degrees of dominance
- In menders experiment he worked with traits that shows complete dominance
- homozygous dominant and heterozygous dominant are phenotypically the same
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Define incomplete dominance
neither alleles is finally dominant
- F1 gen has a phenotype that is mixed with the parental genes
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What is codominance
2 alleles that affect phenotype are not expressed
- Multiple alleles
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what are multiple alleles
genes that exist in multiple forms with more than 2 alleles
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What does "multiple genes" mean and what are some examples of it
In many cases, 2 or more genes are responsible in determining phenotypes
Epistasis
Polygenetic inheritance
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what is epistasis
one gene locus mask or modifies phenotype of second gene locus
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what is polygenetic inheritance
affect of 2 or more genes acting on single phenotype
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What is a sex-linked gene
a gene located either x or Y chromosome
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who found the sex-linked chromosome and how did they find it
Thomas Morgan hunt experimented with fruit flies and determined that specific genes can be carried on sex chromosomes
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what is a y-linked genes
genes specifically found on the Y chromosome
-very few y-linked genes and very few disorderes
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what are x-linked genes
genes found on the x chromosome
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What is the inheritance of sex-linked genes
fathers can pass all of their x-linked alleles to their daughters, but no sons
mothers can pass all of their y-linked alleles to both children
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What is the inheritance of x-linked genes
if the x-linked gene is due to recessive...
- females will only express that trait if they inherit it from their mother
- males only have on X chromosome, so they will express that trait if they inherit it from their mother
- called hemizygous
- males are much more likely to have x-linked trait
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What are 3 x-linked disorders and define them
Duchenne muscular distrophy: progressive weakening of the muscles
Hemophilia: inability to properly clot blood
Color blindness: inability to correctly see colors
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What is the locus
location of gene on chromosome
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What is an allele:
different form of a gene
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What are the 2 laws that go with chromosomes
law of seg and law of indep asssort
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What is Drosophilia melanogaster
2 week generations
4 chromosomes (3 outcomes and 1 sex)
Ex: fruit flies
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What is a wild type of gene
what exists in nature has + superscript
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What are sex-linked genes
carried on x chromosome
-hetero females are acrriers, they can pass allele to offspring w/out showing symptoms
- females get disease if they inherit both recessive x alleles
- man are more likely to have diseases because they only have 1 x chromosome
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What are linked genes
genes on same chromosome are usually inherited together
-not inherited together if crossing over takes place between genes
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What is a parental type
offspring's phenotype resembles parents
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What is recombint
offspring genotype is different from parental and offsprings genotype is new combination of patental genes
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