exam #3 vocab Flashcards
chromosomes
the structures that contain most of the cell’s DNA
asexual reproduction
the creation of genetically identical offspring by a single parent, without the participation of sperm and egg
sexual reproduction
requires fertilization of an egg by a sperm
gametes
egg and sperm
haploid
sex chromosome
binary fission
dividing in half
chromatin
fibers composed of roughly equal amounts of DNA and protein molecules
sister chromatids
contain identical copies of the DNA molecule
- two sister chromatids are joined together especially thightly at a narrow “waist” called the centromere
cell cycle
ordered sequence of events that extends from the time a cell is first formed from a dividing parent cell until its own division into two cell
interphase
when a cell’s metabolic activity is very high and the cell performs its various function within the organism
mitotic phase (M phase)
the part of the cell cycle when the cell actually divides, accounts for only about 10% of the total time required for the cell cycle
mitotic spindle
football shaped structure of microtubules that guides the separation of the two sets of daughter chromosomes
centrosomes
clouds of cytoplasmic material that in animal cells contain pairs of centrioles
cleavage furrow
a shallow indentation in the cell surface
growth factor
a protein secfreted by certain body cells that stimulates other cells to divide
density-dependent inhibition
phenomenon in which crowded cells stop dividing
cell cycle control system
cyclically operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle
tumor
an abnormally growing mass of body cells
benign tumor
if abnormal cells remain at the original site, the lump is benign
malignant tumor
can spread into neighboring tissues and other parts of the body, displacing normal tissues and interrupting organ function as it goes
metastasis
spread of cancer cells beyond their original site
carcinomas, sarcomas, lymphomas
- skin or lining of the intestine (car)
- tissues that support body, bone and muscle (sar)
- bone marrow spleen and lymph nodes (lymph)
somatic cell
typical body cell
homologous chromosomes
two chromosomes of a matching pair
- they both carry genes controlling the same inherited characteresitcs
locus
gene located at a particular place
sex chromosomes
determine an individual’s sex
- male/female X/Y
autosomes
the 22 remaining pairs of chromosomes
life cycle
development of a fertilized egg into a new adult organism - sequence of stages leading from the adults of one generation to the adults of the next
diploid
body cells contain pairs of homologous chromosomes
haploid
cell with single chromosome set
n = 23
fertilization
haploid sperm cell from the father fuses with a haploid egg cell from the mother
zygote
fertilized egg and sperm
- diploid
- 2 sets of homologous chromosomes
meiosis
type of cell division that producds haploid gametes in diploid organism
crossing over
an exchange of corresponding segments between nonsister chromatids of homologous chromosomes
chiasma
the sites of crossing over appear as x-shaped regions
genetic recombination (recombinant)
the production of gene combinations different from those carried by the original parental chromosomes
heredity
the transmission of traits from one generation to the next
genetics
scientific study of heredity
character
a heritable feature that varies among individuals, such as a flower color
trait
each variant for a character, such as purple or white flower
monohybrid cross
parent plants differ in only one character
homozygous
two identical alleles for a gene
homozygotes for the trait
heterozygous
organism that has two different alleles for a gene (heterozygotes)
dominant
if two alleles of an inherited pair differ, then one determines the organisms appearance
recessive
organism that has two different alleles for a gene
- heterozygote
locus
each labeled band on the chromosomes
- specific location of a gene along chromosomes(loci)
phenotype
physical trait
genetype
genetic makeup
dihybrid cross
mating of parental varieties differing in two characters
complete dominance
the dominant allele has the same phenotypic effect whether present in one or two copies
incomplete dominance
the appearance of F1 hybrid falls between the phenotypes of the two parental varieties
codominant
both alleles are expressed in heterozygous individuals
polygenic inheritance
the additive effects of two or more genes on a single phenotypic character
sex-linked gene
gene located on either sex chromosome - X, Y
molecular biology
study of heredity at the molecular level
bacteriophages or phages
viruses that exclusively infect bacteria
nucleotides
DNA and RNA are nucleic acids, consisting of long chains (polymers) of chemical units (monomers)
DNA
deoxyribonucleic acid
semiconservative model
in DNA replication where half of the parental molecule is maintained in each daughter molecule
DNA polymerases
the enzymes that link DNA nucleotides to a growing daughter strand add nucleotides only to the 3’ end of the strand never to the 5’ prime
- grows 5’ - 3’
DNA ligase
enzyme that links or ligates pieces of DNA into a single DNA strand
transcription
synthesis of RNA
translation
synthesis of protein under direction of RNA
Function of gene
to dictate the production of a polypeptide
- provide instructions for making specific proteins
- does not build protein directly
codons
genetic instructions for teh amino acid sequence of a polypeptide chain are written in DNA and RNA as a series of non over lapping three base “words”
genetic code
set of rules that relate codons in RNA to amino acids in proteins
RNA polymerase
a transcription enzyme that links the RNA nucleotides
promoter
the “start trancribing” signal
- nucleotide sequence
3 phase of transcription
1 initiation - attach rna polymerase to promoter and starts RNA synthesis
2 elongation - RNA grows longer - done RNA strand peels away and DNA strands come together again
3 termination - RNA polymerase reach a terminator and detaches from RNA molecule and gene
mRNA
- messenger RNA
- encodes amino acid sequences
ribosomes
structures in the cytoplasm that position mRNA and tRNA close together and catalyze the synthesis of polypeptides
mutation
any change in the nucleotide sequence of DNA
silent mutation
some substitution mutations that has no effect at all
lytic cycle
results in the lysis (breaking open) of the host cell and the release of the viruses that were produced within the cell
lysogenic cycle
viral DNA replication occurs without destroying the host cell
plasmid
a small, circular DNA molecule separate from the bacterial chromosome
gene regulation
the turning on and off of genes
- can help organisms respond to environmental changes
gene expression
the overall process by which genetic information flows from genes to proteins
- from genotype to phenotype
the control of gene expression makes it possible for?
cells to produce specific kinds of proteins when and where they are needed
differentiation
cells specialized in structure and function with each type of cell fulfilling a distinct role
results: body contains hundreds of different types of cells
histones
small proteins that plays a crucial aspects with DNA packing
nucleosome, linkers, tight helical fiber, thick supercoil
8 histones surrounded by DNA “bead”, that is joined by “linkers” strings which is wrapped into a tight helical fiber which is coiled into a thick supercoil
epigenetic inheritance
inheritance of traits transmitted by mechanism not directly involving the nucleotide sequence
alternative RNA splicing
organisms canproduce more than one type of polypeptide from a single gene
regulation of gene expression
Breakdown of mRNA
initiation of translation
protein activation
protein breakdown
reproductive cloning
cloning that results in the birth of a new living individual
therapeutic cloning
when the major aim is to produce embryonic stem cells for therapeutic treatments
oncogene
a gene which can cause cancer when present in a single copy in the cell
proto-oncogene
a normal gene that has the potential to become an oncogene
tumor suppressor genes
genes who’s normal products inhibit cell division
- help prevent uncontrolled cell growth
biotechnology
the manipulation of organisms or their components to make useful products
DNA technology
modern laboratory techniques for studying and manipulating genetic material
Recombinant DNA
formed when scientists combine nucleotide sequences (pieces of DNA) from two different sources–different species– to form a single DNA molecule
genetic engineering
direct manipulation of genes for practical purposes
gene cloning
the production of multiple identical copies of a gene-carrying piece of DNA
vector
gene carrier
DNA ligase
joins DNA molecules by covalent bonds
restriction enzymes
bacterial enzymes that are used as a cutting tool
restriction site
the DNA sequence recognized by a particular restriction enzyme
restriction fragments
the pieces of DNA produced by cuts made by restriction enzymes
GMO
genetically modified organisms
- organisms that have acquired one or more genes by artificial means
gene theraphy
alteration of an afflicted individuals genes for therapeutic purposes
DNA profiling
the analysis of DNA samples to determine whether they cam e from the same individuals
PCR
polymerase chain reaction
- a technique by which a specific segment of a DNA molecule can be targeted and quickly amplified in the laboratory
gel electrophoresis
thin slab of jellylike material that acts as a molecular sieve that separate macromolecules (usually proteins or nucleic acids) on the basis of size, electrical charge or other physical properties
cell division
when cell undergoes reproduction, the two daughter cells that result are gentically identical to each other and to the original parent cell
