Test 3 Vocab Flashcards
genome
all the DNA in a cell
chromatin
an uncondensed (less condensed) complex of DNA + protein (histones)
gene
unit of information that specifies an organism’s inherited traits
chromosomes
consist of condensed chromatin
replicated (duplicated) chromosome
consists of two sister chromatids
sister chromatid
joined copies of the original chromosome (one half of a replicated chromosome)
centromere
specific DNA sequence where chromatids are attached most closely to one another by protein structure known as kinetrochore
unreplicated chromosome
used once sister chromatids have separated
somatic cells
nonreproductive cells, have two sets of chromosomes
chromosomes in human cell
2 sets of 23 chromosomes, one from each parent, equaling 46
gametes
reproductive cells (sperm and eggs), have half as many chromosomes as somatic cells
chromatin
loosely coiled form of DNA found in the nucleus; normal state of DNA when cell is not dividing
G1 phase
cell grows and does normal cell functions
S phase
cell copies its DNA (chromosomes) in preperation for cell division; each duplicated chromosome has two sister chromatids
G2 phase
cell keeps growing, produces more organelles in anticipations of cell division
mitosis
division of the nucleus and all nuclear material (including DNA); stages: prophase (including prometaphase), metaphase, anaphase, telophase
prophase
chromatin strands tightly coil (condense) into chromosomes (visible with microscope); nuceoli disappear; nuclear membrane begins disintegrating; mitotic spindle forms (consists of two pairs of centrioles, microtubule spindle fibers extend from each and begin to attach to kinetochores, asters also extend away from centrioles)
asters
small microtubule fibers that “star” out from the centrioles
metaphase
longest stage of mitosis; centrosomes have now moved to opposite poles; spindle fibers have aligned chromosomes along the center axis (metaphase plate/equator) of the cell
anaphase
shortest phase; cohesion proteins holding each pair of sister chromatids together are cut, freeing sister chromatids, now separate chromosomes; spindle fibers attached to kinetochores shorten pulling sister chromosomes to opposite sides of the cell
telophase
each pole of cell now has identical collections of chromosomes; new nuclear membranes begin to reform around each set of chromosomes; nucleolus reforms in each new nucleus; chromosomes decondense spindle breaks down
cytokinesis
division of cytoplasm; usually begins while telophase is finishing;
•Animals-involes a righ of actin micropilaments which serve as a “drawstring” that pinches the cell around the middle to from a cleavage furrow; divides cells into 2 cells each containing its own nucleus, cytoplasm, and organelles
•Plants-involves formation of a cell plate
cleavage furrow
shallow groove in cell surface
cell plate
material for a new cell wall is laid down between two poles of the cell
control checkpoints
where the cell halts the cell cycle and evaluates conditions to decide if the cycle should continue; allows cell to determine if the proper prerequisite activities have occurred to ensure that the remainder of the cell cycle will proceed normally
G0 phase
cells that abort its plans to divide and enters a nondividing state; some cells can actually be called back to divide when the right growth factors are present. IE liver cells
G1-S checkpoint
near the end of G1, ensures the cell has necessary growth factors, nutrients, and enzymes to synthesize DNA
G2-M checkpoint
at the end of G2, ensures that DNA replication is finished before cell begins mitosis
kinases
are enzymes that activate or inactivate other proteins by phosphorylating them
cyclin
protein that cyclically fluctuates concentrations in the cell, binds to kinases and activates it
metaphase-anaphase checkpoints
at the end of metaphase, prevents anaphase until all kinetochores are properly attached to spindle fibers along the cell’s midplane
faulty checkpoints
cells with “faulty” checkpoint quality control allow defective cells to divide and propagate
tumor
a mass of abnormal cells within otherwise normal tissue
benign tumor
does not spread to other body tissues
malignant tumor
(cancerous tumor): able to migrate from its original site to other body tissues and organs, where it often impairs functions
matastasis
when cancer cells break away from the tumor and travel to distant body location
cancer cells
uncontrolled growth (mitosis) of abnormal (malignant) cells
heredity
(inheritance); transmission of traits from one generation to the next
genes
discrete regions of DNA code on a chromosome that contain instructions to build proteins that confer specific traits
alleles
variants of a particular kind of gene
mutations
are changes in a organism;s DNA
locus
the specific spot on a chromosome where a specific gene is located
asexual reproduction
one parent passes copies
of all its gens to offspring without fusion of gametes; mitosis in eukaryotes and binary fission in prokaryotes
sexual reproduction
usually involves, two parents which give rise to genetically unique offspring, regardless of DNA mutations
zygote
created during sexual reproduction; completed by two cells (gametes) which fuse together to form a single cell
fertilization
union of gamets (fusion of nuclei); results in diploid cell called a zygote
diploid
(2n): two sets of chromosomes; parental cells have two of every kind of chromosome (one is maternal and the other paternal in origin)-use the expression 2n denote the two of every kind of chromosom
haploid
(n); one set (half the number) of chromosomes; condition when a cell has only one of each kind of chromosome; in human cells this is only found in gamete cells
autosomes
most chromosomes contain information that does not determine gender
sex chromosomes
a couple chromosomes (X and Y) contain information that determines gender; female XX and mail XY
karyotypes
visual display of condensed chromosomes arranged in homologous pairs
homologous chromosomes (homologs)
matching chromosomes (one from each parent) that carry genes for the same types of traits
meiosis I
primary function of meiosis I is to do crossing over and separate homologs from each other thus, reduce chromosome number from dipoid to haploid
prophase I
nuclear membrane disintegrates; chromatin condenses into chromosomes; spindle form and connects to chromosomes; synapsis and crossing over occur
synapsis
homologous chromosomes pair up and are connected together through a special protein structure called the synaptonemal complex
crossing over
homologous chromosomes exchange equivalent peices of their chromosome arms containing alleles; crucial step that allows chromosomes to acquire new combinations; recombinant chromosomes
recombinant chromosomes
chromosomes that carry genes (DNA) derived from two different parents
metaphase I
homologous pairs line up on the mataphase plate randomly (independent assortment)
independent assortment
is how one pair lines up has no influence on how the other chromosomes (with their alleles) line up; helps create new daughter cells with varied collections of chromosomes (and alleles)
anaphase I
homologous pairs are separated from each other and moved to opposite poles; each pole must receive one chromosome from each homologous pair (remember each chromosome also has a sister chromatid still attached to the kinetochore in the centromere regaion
telophase I and cytokinesis
two cells form, each containing a haploid number of chromosomes; cytokinesis proceeds similarly as described in mitosis; chromosomes may or may not decondense and nuclear membrane may or may not reform; ther eis no duplication of chromosomes
meiosis II
primary purpose of meiosis II is to separate sister chromatids from each other
prophase II
chromosomes fully condense; nuclear membrane disappears (if it did reform after telephase I); spindle finbers conncect to kinetochores on individual sister chromatids
metaphase II
chromosomes line up at metaphase plate
anaphase II
sister chromatids separate and are pulled to opposite sides of the cell (at this point, they are called daughter chromosomes (unduplicated chromosomes))
telophase II and cytokinsis
chromosomes decondense and nuclear membrane reforms; cytokinesis proceeds to divide cytoplasm into two new cells; since meiosis I produced two daughter cells which proceeded into meiosis II, at the end of meiosis II we produce a total of 4 haploid, genetically unigue cells
nondisjunction
either pairs of homologous chromosomes or sister chromatids do no separate normally during meiosis
aneuploidy
is the result from the fertilization of gamets in which nondisjunction occurred
down syndrome
is an aneuploidy condition that results from three copies of chromosome 21
genetics
the study of heredity
phenotype
physical appearance; description of a characteristic/trait
genotype
genetic makup; listing of 2 alleles one from each parent; capital letter for dominant and lower case for recessive
dominant
masks or cover up the presence of other alleles; is fully expressed in the phenotype of heterozygote (AKA what we “see”)
recessive
alleles that are masked; are hidden, we don’t “see” their effect on organism’s phenotype in heterozygote
homozygous
organism with two identical alleles for a trait; homozygous dominant (PP) or homozygoud recessive (pp)
heterozygous
organism that has two different alleles for a gene
true-breeding
organisms that produce offspring of the same variety over many generations when they self fertilize
self fertilize
fertilization within the same organism
cross fertilization
fertilization between different plants
hybridization
is a mating (crossing) of 2 contrastion true-breeding varieties
P (parental) generation
the true-breeding parents
F1 (filial) generation
the hybrid offspring (Pp) of the P generation
F2 generation
the offspring that results when the hybrid offspring of the F1 generation either self polinate or cross-pollinate with other F1 hybrids
punnett square
a diagram for predicting the results of a genetic cross between individuals of known genetic makeup
testcross
breeding the unknown individual with a homozygous recessive individual
law of segregations
the two alleles of a gene segregate during meiosis and each gamete carries only one allele of each pair
law of independent assortment
each pair of alleles segregates independently of each other pair of alleles during gamete formation
single factor cross
are concerned when a single genetic trait is passed from parents to an offspring
monohybrid crosses
a cross between two organisms that are heterzygous for one gene (trait) being followed
double factor cross
when two pairs of alleles (traits) are gollewed from the parental generation to the offspring
dyhybrid crosses
a cross between two organisms that are each heterosygous for two genes being followed
multiplication rule
the probability that two or more independent events will occur together is the product of their individual probabilities
addition rule
probability that any one of two or more exclusive events will occur is calculated by adding together their individual probabilities
Complete dominance:
occurs when phenotypes of the heterozygote and dominant homozygote are identical
Incomplete Dominance
occurs when the allele of neither parent is fully expressed in the heterozygote and the offspring’s phenotype is intermediate between that of the two
homozygous parents
Codominance
When the phenotypes of both alleles of a gene are exhibited in the heterozygote
Multiple Alleles
When 3 or more alleles for a given locus (a gene) exists in a given population
Pleiotropy
Ability of a single gene to have multiple affects on several phenotypic characteristics
Epistasis
a gene at one locus alters the phenotypic expression of a gene at a second locus
Polygenic Inheritance
alleles at several loci affect a single phenotypic trait expression
Pedigree
is a chart that shows how a trait and the genes that control it are inherited within a family
Carrier
an individual who carries a recessive trait that is not expressed; heterozygous individuals who carry the recessive allele but are phenotypically normal
Autosomal Recessive
Conditions
Recessively inherited conditions show up only in individuals homozygous for the allele
Autosomal Recessive
Disorders
Genetic Disorder: allele change that would affect the ability of a person to survive under normal circumstances and without treatment
Tay-Sachs disease
a dysfunctional enzyme causes an accumulation of lipids in the brain
Cystic fibrosis
allele results in defective or absent chloride transport channels in plasma membranes
Sickle-cell disease
caused by the substitution of a single amino acid in the
hemoglobin protein in red blood cells
Autosomal Dominant Conditions & Disorders
Genetic Disorder: a dominant allele that would affect the ability of a person to survive under normal circumstances and without treatment; Condition can survive
Polydactyly
conditions where an individual has more than 5 fingers or toes per hand or foot
Progeria (Hutchinson)
produces rapid aging in children
Achondroplasia
a form of dwarfism caused by a rare dominant allele
Huntington’s disease
degenerative disease of the nervous system; no obvious phenotypic effects until the individual is about 35 to 40 years of age
Amniocentesis
the liquid (amniotic fluid) that bathes the fetus is removed and tested
Chorionic villus sampling (CVS)
sample of the placenta is removed and tested
Purines
have two organic rings, Adenine(A), Guanine(G)
Pyrimidine
have one organic ring, Thymine(T), Cytosine(C)
Antiparallel
The sugar phosphate backbone units run in opposite directions; 5’ end with the phosphate group attached to the 5’-‐C in the sugar ring
complimentary
each stores the information necessary to reconstruct the other
Semiconservative Model
when a double helix replicates, each daughter molecule will have one old strand (derived or “conserved” from the parent molecule) and one newly made strand
origins of replication
where the two DNA strands are separated, opening up a replication “bubble”; consist of short stretches of DNA having a specific sequence of nucleotides
replication fork
a Y-‐shaped region where parental strands of DNA are being unwound
DNA helicases
enzymes that untwist the double helix at the replication forks
Single-‐strand binding proteins (SSBs)
proteins that bind to each unwound strand keeping them from re-‐paring
Topoisomersase
enzymes that break and rejoin the parental DNA ahead of the replication fork relieving the strain caused by unwinding (help keep DNA from “tangling” once unwound)
Primase
enzyme that synthesizes RNA primer
RNA primer
RNA chain needed to initiate DNA synthesis
transcription
the synthesis of RNA using information in DNA
mRNA
carries a genetic message from the DNA to the protein synthesizing machinery of the cell
translation
sythesis of a polypetide (protein) using information in the mRNA
triplet code
is genetic information (instructions) for proteins are written in DNA as 3-nucleotide word
codons
triplet code of DNA on the template strand is transcribed into complementary 3-nucleotide words in mRNA
initiation
RNA polymerase binds to promoter, DNA strand unwid, RNA polymerase initiates RNA synthesis at start point
TATA box
nucleotide sequence containing TATA within the promoter
transcription factors
proteins that bind to TATA box to mediate binding of RNA polymerase II
elongation
RNA polymerase continues to unwind helix, adding RNA nucleotides
termination
RNA transcript (pre-mRNA) is released upon reaching the polyadenylation signal (AAUAAA) and RNA polymerase detaches from DNA
5’ cap
modified guanin nucleotide added to 5’ end of RNA transcript (pre-mRNA)
poly-A tail
50-250adenin (A) nucleotides, added to the 3’ end of the pre-mRNA
intron
noncoding segments of nucleic acid that lies between coding regiods
exons
coding segment of nucleic acid
transfer RNA (tRNA)
transfer or carries an amino acid from cytoplasm to a growing polypeptide in a ribosome, tRNA is complementary to mRNA
anticodon
nucleotide triplet on tRNA that base pairs to a complementary codon on mRNA
wobble
flexible base pairing at the 5’ end ( third nucleotide base) of anticodon
ribosomes
facilitate the specific coupling of tRNA anticodons with mRNA codons during protein synthesis
mutation
changes to the genetic information
substitutions
replaces one nucleotide and its partner with another pair of nucleotides
silent mutations
changes in a single nucleotide that have no effect on the amino acid produced by codon because of redundancy in the genetic code
missense mutations
changes in a single nucleotide that still code for an amino acid, but not the correct amino acid
nonsense mutations
change in a single nucleotide that changes an amino acid codon into a stop codon, nearly always leading to nonfunctional protein
insertions or delections
additions or losses of nucleotides; may lead to a frameshift mutation
mutagens
physical or chemical agents that can cause mutations
