Bio Midterm 1 Flashcards
DNA is…
semiconservative
DNA has a ___________ backbone
sugar-phosphate
base pairs on DNA are joined by
hydrogen bonds
the sugar-phosphate backbone is joined by
covalent phosphodiester bonds
A:T have ____ hydrogen bonds
2
C:G have ______ hydrogen bonds
3
A:
adenine
T:
thymine
C:
cytosine
G:
guanine
chromatin is…
fibers of DNA
a chromatid is…
DNA wrapped around proteins called histones and nucleosomes
a chromosome is…
two sister chromatids attached by a centromere
homologous
having the same information
a chromosome is made up of
2 homologous chromatids
sex cells are…
haploid
Mitosis phases
PMATC
Prophase major developments:
centrioles appear, nuclear envelope dissolves, chromosomes appear
Metaphase major developments:
centrioles produce spindle fibers, spindles push chromosomes to middle, chromosomes line up along metaphase plate
Anaphase major developments:
chromosomes are broken into chromatids, chromatids move to opposite sides, each side gets one homologous chromatid
Telophase major developments:
nucleus reforms, cell membrane pinches in, still sharing cytosol
chromatids “move” because…
kinetochores in the centromere destroys spindle fibers
Cytokinesis:
cell membrane separates forming 2 identical cells
organism
a living entity made up of cells
theory
an explanation for a very broad class of observed phenomena that is supported by a wide body of evidence
experiments
allow researchers to test the effect of a single, well-defined factor on a particular phenomenon
hypothesis
a statement that can be tested by scientific research
control
checks for factors that might influence the outcome of the experiment
the experimental conditions must be…
as constant as possible
x-axis
independent variable
y-axis
dependent variable
scatterplots
continuous data
bar charts
discontinuous data/categories
histograms
show frequencies in populations
standard error
indicates the uncertainty in a calculated mean
standard deviation
an estimate of the variability of the population that the sample was taken from
p-value
probability of getting various values of the test statistic if the null hypothesis is correct
a difference among treatment groups is statistically significant if…
there is less than a 5% probability of observing it by chance
artificial selection
manipulating the composition of the population by selecting individuals with desirable traits to reproduce
natural selection
individuals with certain heritable traits produce more offspring than do individuals without these traits
evolution by natural selection is a change in…
allele frequencies in a population
evolution by natural selection occurs when heritable variation leads to…
differential reproductive success
biological fitness
the ability of an individual to produce surviving, fertile offspring relative to that ability in other individuals in the population
Adaptation
a heritable trait that increases the fitness of an individual in a particular environment relative to individuals lacking the trait
adaptation increases
fitness
only ______ can evolve
populations
Polygenic
many genes that exert a relatively small effect influence the trait
heredity
transmission of traits from parent to offspring
trait
any observable characteristic of an individual ranging from outward appearance to molecular characteristics
Model organism
a species that is used for research because it is easy to work with and conclusions drawn from studying it may apply to many other species
polymorphic trait
when one trait appears commonly in two or more different forms
phenotype
observable traits in an individual
pure line
individuals that produce offspring identical to the parents when they are crossed to another member of the same pure-line population or self-fertilized
hybrids
offspring from matings between the true-breeding parents that differ in one or more traits
parental generation
individuals used in initial cross
F1
first filial, progeny of parental generation
F2
second filial, progeny of f1
Monohybrid cross
a cross that produces a hybrid for a single trait
reciprocal cross
a set of matings in which the mother’s phenotype in the initial cross is the father’s phenotype in a subsequent cross
Particulate inheritance
hereditary determinants maintain their integrity from generation to generation and act as discrete, unchanging particles
gene
hereditary determinant of a trait
alleles
different versions of the same gene
genotype
the combination of alleles found in an individual
principle of segregation
two members of each gene pair must segregate into different gamete cells during the formation of eggs and sperm
the principle of segregation occurs during…
anaphase 1 and 2
homozygous
having two copies of the same allele
heterozygous
having two different alleles for the same gene
dihybrid
F1 individuals that are heterozygous for both genes
dihybrid cross
mating between dihybrids
principle of independent assortment
alleles of different genes are transmitted independently of one another, producing 4 phenotypes in a 9:3:3:1
the principle of independent assortment occurs during…
metaphase 1
testcross
a parent with a dominant phenotype but unknown genotype is crossed with a parent that contributes only recessive alleles
meiosis
nuclear division that leads to a halving of chromosome numbers and ultimately to the production of sperm and egg
karyotype
the number and types of chromosomes in a cell
haploid number
the number of distinct types of chromosomes
ploidy
the number of chromosome sets
zygote
the diploid cell that results from fertilization
wild type
common phenotype
mutation
a heritable change in a gene
mutant
an individual with an unusual phenotype due to a mutation
genetic locus
a particular position on a chromosome
linkage
the tendency of alleles of particular genes to be inherited together
recombinant chromosomes
generated during crossing over in prophase of meiosis 1
genetic map
a diagram showing the relative positions of genes along a particular chromosome
multiple allelism
the existence of more than two common alleles of the same gene
pleiotropic
a gene that influences many traits
gene interactions
when two or more genes influence a single trait
chromosome theory of inheritance
hereditary information is encoded in units called genes that are located on chromosomes
central dogma
DNA codes for RNA, RNA codes for proteins
ATP (adenosine triphosphate)
chemical energy
species
distinct, identifiable types of organisms
deoxyribonucleotides are…
monomers that polymerize to form DNA
3 nucleic acids code for…
1 amino acid
messenger RNA (mRNA)
single-stranded molecules of RNA carry information out of the nucleus from DNA to the site of the protein synthesis in the cytoplasm
RNA polymerase
an enzyme that uses DNA to synthesize a complementary RNA molecule
transcription
the process of using a DNA template to make an RNA molecule that has a base sequence complementary to the DNA
translation
the process of using the information in the base sequence of mRNA to synthesize proteins
mutation cause a change in…
genotype and create new alleles
point mutation
a mutation that alters the sequence of one or a short number of base pairs
Missense mutation
a point mutation that changes the identity of an amino acid in a protein
frameshift mutation
a mutation that shifts the reading frame
silent mutation
a point mutation that does not change the amino acid sequence of the gene product
nonsense mutation
occurs when a codon that specifies an amino acid is changed to a stop codon
3 categories of mutations:
beneficial, neutral, deleterious
aneuploidy
the addition/deletion of individual chromosomes
4 major structural changes after chromosome mutation:
deletion, inversion, duplication, translocation
overlapping standard error bars
cannot reject the null hypothesis
crossing over is the physical basis of…
recombination
structural region of a gene
codes for an RNA or protein that functions in the cell
regulatory region of a gene
is responsible for the expression of a gene
