Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
162 Cards in this Set
- Front
- Back
DNA |
deoxyribose nucleic acid; how eukaryotic cells carry their genetic information |
|
What is DNA made of? |
deoxyribose, phosphate and a nucleotide |
|
Who discovered the structure of DNA? |
Watson and Crick with the help of franklin |
|
purines |
adenine and guanine due to similar structures |
|
pyridamines |
cytosine and thymine with similar structures |
|
adenine pairs with? |
thymine |
|
guanine pairs with? |
cytosine |
|
how was DNA to be shown as helical? |
xray cartography by franklin showed an X |
|
How are the bases of DNA joined together? |
hydrogen bonds |
|
how many bonds are between A and T |
2 hydrogen bonds |
|
how many bonds are between C and g? |
3 hydrogen bonds |
|
antiparallel |
opposite, running the opposite direction |
|
complementary strand |
each strand contains the paired bases to the other strand |
|
essential property of genetic material |
the ability to copy itself. |
|
origins of replication |
specific nucleotide sequence that initiates the replication process
|
|
helicases |
required to initiate DNA replication by breaking the hydrogen bonds |
|
dna polymerase |
enzyme that catalyzes the synthesis of a new DNA strand |
|
replication bubble |
the localized regions of synthesis which form at the many origins of replication along the DNA molecule |
|
replication fork |
at the ends of the bubble where the strands of DNA are separated into a fork |
|
bidirectional |
the two replication forks move in opposite directions |
|
Which direction does DNA polymerase syntehsize in? |
5'-3' |
|
leading strand |
newly synthesized DNA that is continuous from the beginning of replication |
|
lagging strand |
newly synthesized DNA that is in fragments |
|
okazaki fragments |
fragmented DNA of lagging strand |
|
DNA ligase |
connects the okazaki fragments |
|
daughter cells |
the contents of a cell are split between two new cells |
|
why does replication occur? |
to replace old cells, growth, or reproduction |
|
mitosis |
nuclear division; a complete set of previously duplicated chromosomes is allocated to each of the daughter cells nuclei |
|
cytokinesis |
a process that divides the entire cell into two new cells |
|
cell cycle |
a regular, repeated sequence after and before mitosis |
|
interphase |
precedes and follows mitosis divided into three phases; G1, S1 and G2 |
|
M-phase |
cytokinesis and mitosis together |
|
initials |
plant cells that pass through successive cell cycles |
|
apical meristem |
immediate derivatives of initials located at the tips of roots and shoots |
|
G0 phase |
when the initials arrest the cycle due to environmental factors causing dormancy |
|
endoreduplication |
the continued DNA replication before a cell undergoes differentiation |
|
what is the purpose of endoreduplication? |
to increase the level of gene expression |
|
checkpoints |
crucial transition points in the cell cycle. Near the end of G1 and G2 |
|
G1 phase |
increase in size, synthesis of more enzymes, ribosomes, organelles, membrane systems, and other cytoplasmic molecules and structures |
|
S phase |
(synthesis) histones are processed/synthesized |
|
G2 phase |
checks the chromosome replication is complete and any DNA damage is repaired
|
|
centrioles |
(not in fungi and plants) formation of spindle fibers for separation of chromosomes |
|
centrosomes |
cloud surrounding centrioles |
|
what happens in a plant that doesn't happen in animal mitosis? |
the vacuole divides, the nucleus goes to the center and a cell plate forms for cytokinesis |
|
how is the nucleus anchored in the plant cell for mitosis? |
cytoplasmic strands |
|
phragmosome |
cytoplasmic strands that after anchoring the nucleus merge to form a sheet that bisects the plant cell. |
|
preprophase band |
dense band of microtubules encircling the nucleus on a plane corresponding to the equatorial plane of the future mitotic spindle appears during phase G2 |
|
cell plate |
the initial partition between the daughter cells appearing in telophase |
|
how does the cell plate form? |
inside to the outside |
|
what is the order of the phases of mitosis |
prophase, metaphase, anaphase, telophase, cytokinesis |
|
prophase |
first stage of mitosis; chromatin condenses into chromosomes, chromatids align and bind together, and nuclear envelope disappears |
|
sister chromatids |
the initial and duplicated chromatin that "pair" together to make a chromosome |
|
centromere |
the region where the two sister chromatids are held together |
|
metaphase
|
after prophase; chromatids are aligned in the center of the cell by microtubules
|
|
mitotic spindle |
a 3-d structure that is widest in the middle and tapers towards its poles; appears where the nucleus was |
|
spindle fibers |
bundles of microtubules |
|
kinetochores |
spindle microtubules that become attached by protein complexes to either side of each chromosome |
|
kinetochore microtubules |
microtubules attached to the kinetochore |
|
polar microtubules |
spindle microtubules that extend from pole to pole and consists of two halves |
|
how are spindle fibers oriented? |
minus end at the poles and plus end pointing away from the pole |
|
anaphase |
after metaphase; the separation of the sister chromatids to opposite poles by the microtubules and at the centromeres are disconnected. |
|
daughter chromosomes |
separated sister chromatids |
|
how do the sister chromatids get moved to the poles? |
the center is dragged along by a motor protein on the spindle fiber and the end of the spindle fiber is shortened behind it. |
|
motor proteins |
use ATP to pull the chromosomes along the microtubules to the poles |
|
telophase |
final stage of mitosis; nuclear envelopes form, the spindle disappears, and the chromosomes elongate |
|
what is the longest stage of mitosis? |
prophase |
|
phragmoplast |
barrel shaped system of microtubules; overlapping microtubules; constructs the cell plate using vessicles |
|
are chromosomes different lengths |
yes |
|
chromatin |
the combination of DNA and its associated proteins |
|
what is chromatin mostly composed of? |
proteins |
|
histones |
positively charged, basic and attracted to DNA; synthesized in large amounts during S phase; folding and packaging of DNA |
|
nucleosomes |
the fundamental packing units of chromatin; core of 8 histones with DNA wrapped twice around |
|
RNA |
ribonucleic acid; half strand of DNA composed with ribose not deoxyribose |
|
where is RNA mostly found |
cytoplasm |
|
Path of DNA to proteins |
DNA>mRNA>tRNA>rRNA |
|
what is the template for mRNA |
DNA |
|
mRNA |
messenger RNA; synthesized from DNA strand through transcription; U replaces T; carries genetics to ribosomes |
|
RNA polymerase |
catalyzes the transcription of DNA to mRNA |
|
rRNA |
ribosomal RNA; composes ribosomes with proteins
|
|
where does protein synthesis occur? |
ribosomes in the cytosol |
|
tRNA |
transfer RNA; molecules that are each specific for a particular amino acid |
|
translation |
the synthesis of a polypeptide directed by the nucleotide sequence of the mRNA |
|
replication |
the synthesis of an entire DNA molecule
|
|
how many different amino acids are there? |
20 different amino acids |
|
genetic code |
DNA encodes for proteins (amino acids) |
|
codon |
a set of three nucleotides that sequence one amino acid
|
|
promotor |
binding site for RNA polymerase and determine where transcription begins |
|
terminator |
a sequence that stops transcription |
|
anticodon |
a sequence of 3 nucleotides that binds to the codon on an mRNA molecule |
|
aminoacyl-tRNA |
a tRNA with an attached amino acid |
|
aminoacyl-tRNA synthetase |
connects the tRNA to its amino |
|
How many subunits does a ribosome have? |
2, one larger than the other |
|
mRNA-binding site |
binds the ribosome to the mRNA for transcription |
|
A site |
aminoacyl site; where the incoming amino binds |
|
P site |
(peptidyl) site; where the tRNA bearing the growing polypeptide chain resides |
|
E site |
exit site; from which the tRNAs leave the ribosome after they have released their amino acids |
|
translation
|
initiation, elongation, termination |
|
initiation stage |
smaller ribosomal subunit attaches to mRNA near its 5' end and exposing the first codon, then larger subunit attaches and binds MET to A site |
|
elongation stage |
the second codon of mRNA is positioned opposite the vacant ribosomal A site, a tRNA binds to the mRNA and its amino acid occupies the A site of the ribosome. A peptide bond is formed between the two. The first tRNA is released via E site and returns to the cytosol |
|
peptidyl transferase |
activity of the larger ribosomal subunit forges a peptide bond between the two amino acids |
|
polysome/polyribosome |
a group of ribosomes translating the same mRNA strand |
|
termination stage |
when the ribosome gets to the stop codon and releases the mRNA
|
|
stop codon |
stops translation at UAG, UAA or UGA |
|
what is so special about a stop codon in relation to the tRNA |
there are no tRNA that match the stop codon |
|
release factors |
cytoplasmic proteins that bind directly to a stop codon at the A site |
|
polypeptide/protein targeting and sorting
|
attachment to the ER early on in the translational process. As the proteins are synthesized they are transferred across the membrane
|
|
cotranslational import |
proteins are synthesized and transferred into or across a membrane |
|
how many cells does mitosis create? |
2 diploid cells |
|
how many cells does meiosis create? |
4 haploid cells |
|
zygote |
a gamete cell that unites with another gamete to produce a diploid cell |
|
spore |
a cell that can develop into an organism without another cell |
|
how do spores divide? |
mitotically to produce organisms that are haploid (gametes are produced through mitosis) |
|
stages of meiosis |
prophase 1, metaphase 1, anaphase 1, telophase 1, prophase 2, metaphase 2, anaphase 2, telophase 2, cytokinesis |
|
prophase 1 |
chromosomes condense, homologous pairs form; crossing over occurs |
|
synapsis |
pairing of homologous chromosomes |
|
bivalents |
associated pairs of homologous chromosomes made of 4 chromatids |
|
synaptonemal complex |
unites the homologs |
|
crossing over |
during the time when then synaptonemal complex is existent, portions of the chromatids break apart and rejoin with corresponding segments from their homologous chromatids |
|
chiasma |
the x-like configuration where crossing over occurs |
|
metaphase 1 |
the spindle appears, attaches to the centromeres and moves the paired (2) chromosomes to the middle (random assortment) |
|
anaphase 1 |
homologous chromosomes are split apart and move towards the poles |
|
telophase 1 |
the chromosomes relax, nuclear envelopes before, spindle disappears, nucleolus reforms |
|
prophase II |
chromosomes condense, nucleus disappears
|
|
metaphase II |
spindle forms, sister chromatids line up in the middle |
|
anaphase II |
centromeres separate with the daughter chromosomes move to opposite poles |
|
telophase II |
nucleus forms and chromosomes relax (cytokinesis occurs afterwards) |
|
genetic recombination |
recombination of the genetic material from two parents |
|
mutation |
any change to the hereditary makeup of an organism |
|
chromosome mutations |
a piece may be deleted, duplicated, or inverted; # of chromosomes are altered |
|
point mutation |
only one or a few nucleotides are changed spontaneously or induced by mutagens (sometimes mispairings) |
|
mutagens |
agents that affect DNA; radiation |
|
deletions |
when segments of a chromosome are lost |
|
duplication |
when a segment of a chromosome is duplicated |
|
plasmids |
small circular molecules of DNA separate form the main chromosome, may reenter at places where they share sequences |
|
transposons |
genes that move as small segments of DNA |
|
position effects |
neighboring genes affect the transposon or vice versa |
|
inversion |
when two breaks in a chromosomal segment occur and the segment rotates 180 degrees and reattaches |
|
translocation |
a segment of DNA from one chromosome is exchanged with a segment from another, non homologous one |
|
aneuploidy |
the addition or subtraction of a chromosome |
|
polyploidy |
the duplication of whole sets of chromosomes |
|
how are mutations in haploid organisms vs diploid? |
the haploid mutations are immediately exposed to the surrounding environment (no dominant allele) |
|
heredity |
biological inheritance |
|
genetics |
the study of heredity |
|
sexual reproduction |
regular alternation between meiosis and fertilization |
|
meiosis |
the process of nuclear division in which the chromosome number is reduced from diploid (2n) to haploid (n). Two divisions=four cells with genetic diversity |
|
syngamy/fertilization |
the process by which two haploid cells (gametes) fuse to form a diploid zygote |
|
homologous chromosomes/homologs |
each chromosome has a partner that resembles it in size, shape, and heredity information |
|
allele |
one of two or more alternative forms of the same gene |
|
locus |
where alleles occupy the same space on homologous chromosomes |
|
dominant allele |
the only trait seen when crossing with a recessive trait; it completely covers the other trait |
|
recessive allele |
covered by the dominant trait and never shows in the F1 generation |
|
monohybrid |
cross between individuals that differ by one trait
|
|
genotype |
genetic constitution or alleles present |
|
homozygous |
two of the same alleles |
|
heterozygous |
two different alleles present |
|
phenotype |
physical appearance caused by the genotype |
|
test cross |
the crossing of a homozygous dominant and homozygous recessive |
|
principle of segregation |
heredity characteristics are determined by discrete factors (genes) that appear in pairs; one inherited from each parent; meiosis separates the genes and passes them on (ALLELES OF ONE GENE) |
|
dihybrid |
the crossing of two individuals with two different traits |
|
principle of independent assortment |
the two alleles of a gene assort independently of other alleles (RELATIONSHIPS BETWEEN GENES) |
|
linked genes |
genes located closely together that are usually inherited together |
|
genetic/linkage maps |
provide an approximation of the positions of genes on chromosomes |