Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
BIO 120 Exam 3
| Term | Definition |
|---|---|
| Cell Division | reproduction of cells that is important for growth and development, reproduction, and tissue removal in multicellular organisms |
| Most cell division results in... | genetically identical daughter cells |
| What are the two ways that cell division and reproduction can occur? | mitosis and meiosis |
| Mitosis | occurs in somatic cells, two sets of chromosomes, start with 1 cell and end up with 2 identical daughter cells |
| Meiosis | occurs in germ cells; consists of two rounds of cell division but only one round of DNA replication. It results in cells with half the number of chromosome sets as the original cell; reduces the number of chromosome sets from diploid to haploid |
| How many sets of chromosomes do germ cells have? | 2 |
| How many sets of chromosomes do gametes have? | 1 |
| Where is DNA housed? | in the nucleus |
| Genome | all of your DNA; every cell in your body besides gametes have this |
| Chromosome | DNA wrapped tightly around protein balls called histones |
| Allele | variations of a gene (as in Aa, 'A' is an allele and 'a' is an allele) |
| Locus | location on a chromosome |
| Gene | a segment of DNA along a chromosome expressed into a protein that is inherited |
| Homologous Chrosomes | pair of chromosomes that are not connected; similar in length, shape, and carry the same genes controlling the same inherited characteristics |
| Breakdown of 23 chromosome pairs... | Sex chromosomes have one pair, autosomes have the other 22 pairs |
| Preparation for cell division | DNA is replicated and chromosomes condense |
| During cell division, sister chromatids of each duplicated chromosome... | separate and move into 2 new nuclei, once separate, the chromatids are called chromosomes |
| Phases of the Cell Cycle | Interphase and mitotic phase |
| What phase takes up the majority of the time during the cell cycle? | interphase |
| Parts of interphase | G1- growth, S- copy DNA- replication (homologous chromosomes become sister chromosomes), and G2- growth, get ready for nuclear division |
| What is the G0 phase? | where cells that don't divide (does not receive a signal to divide) go during the cell cycle such as nerve cells |
| What enabled Watson and Crick to deduce that DNA was helical? | X-ray crystallographic images that helped determine the width of the helix, the spacing of the nitrogenous bases, and the number of strands |
| Double Helix | two complementary DNA strands that bind |
| Mitotic Phase | Consists of mitosis- distribution of chromosomes into two daughter nuclei, and cytokinesis- division of cytoplasm, producing two daughter cells which can both start a new cell cycle |
| Short segments of newly synthesized DNA are joined into a continuous strand by... | ligase |
| The first step in the replication of DNA is catalyzed by... | helicase |
| The action of helicase creates... | replication forks and replication bubbles |
| Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments? | DNA polymerase can assemble DNA only in the 5' to 3' direction |
| The synthesis of a new strand begins with the synthesis of a... | RNA primer complementary to a preexisting DNA strand |
| What is responsible for catalyzing the formation of an RNA primer? | primase |
| An old DNA strand is used as a ___ for the assembly of a new DNA strand | template |
| DNA replication is semiconservative which means... | each new double helix consists of one old and new strand |
| Thymine always pairs with | adenine |
| Cytosine always pairs with | guanine |
| DNA strands are antiparallel which means... | A 5' to 3' DNA strand is paired with the 3' to 5' DNA strand |
| Leading strand | synthesis occurs continuously, only one prime needed, daughter strand elongates towards the replication fork |
| Lagging strand | synthesis occurs in segments/discontinuously, multiple primers needed, daughter strand elongates away from the replication fork |
| DNA consists of... | a nitrogenous base, sugar (pentose), and phosphate |
| Pyrimidines | cytosine and thymine/uracil |
| Purines | adenine and guanine |
| In any species the numbers of A and T bases and the numbers of C and G bases are... | always equal |
| How are the nucleotides/bases in DNA connected? | hydrogen bonds |
| What determines if the molecule is DNA or RNA? | the sugar molecules |
| Chromatin | a complex of DNA and protein, found in the nucleus of eukaryotic cells |
| DNA replication | when DNA makes a copy of itself |
| Origin of Replication | site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides |
| Replication fork | y-shaped regions where new DNA strands are elongating and where replication occurs |
| DNA polymerases | catalyze the elongation of new DNA at a replication fork by adding new nucleotides |
| Helicase | untwists the double helix at the replication fork; breaks the hydrogen bonds |
| Single-strand binding proteins (SSB) | binds to and stabilizes single-stranded DNA; holds it open so new nucleotides can be added by polymerases |
| Topoisomerase | corrects "overwinding" or stress ahead of replication forks by breaking, swiveling, and rejoining DNA strands |
| Primase | adds RNA nucleotides (RNA primer) using the parental DNA as a template |
| DNA polymerase requires | a primer and a DNA template strand |
| DNA polymerase can only add nucleotides to which end? | the 3' end |
| In which direction is DNA replicated? | 5' to 3' |
| How is newly made DNA proofread? | DNA polymerases relace any incorrect nucleotides through nucleotide excision repair |
| Nucleotide Excision Repair | A nuclease enzyme cuts out the damaged section of DNA, DNA polymerase fills in the missing nucleotides, and ligase connects the new strand |
| What happens to DNA every time it separates? | It gets shorter due to it ending on a RNA primer |
| The shortening of telomeres is connected to what? | Aging |
| Telomeres | repetitive nucleotide sequences on the end of eukaryotic chromosomal DNA molecules; postpone the erosion of genes near the ends of DNA molecules |
| Telomerase | an enzyme that catalyzes the lengthening of telomeres in germ cells |
| 5 Phases of Mitosis | prophase, prometaphase, metaphase, anaphase, and telophase |
| Prophase | nucleoli disappears, chromosomes appear as 2 identical sister chromatids joined at their centromeres, centrosomes begin to form the mitotic spindle and move away from each other |
| Prometaphase | chromosomes are condensing, microtubules connect to the kinetochores |
| Metaphase | Centrosomes are on opposite polls of the cells and chromosomes line up in the middle |
| Anaphase | the sister chromatids are separated and become daughter chromosomes |
| Telophase | chromosomes become less condensed, remaining spindle microtubules are depolymerized (broke down), nucleoli reappear |
| Cytokinesis | splits the cytoplasm once mitosis is done so that there are two daughter cells (splits at cleavage furrow in animal cells) |
| What regulates the eukaryotic cell cycle? | a molecular control system |
| Cell Cycle Control System | controls the cell cycle (similar to a clock) and is regulated by different checkpoints |
| The frequency of cell division varies with ... | the type of cell |
| MPF (mitosis promoting factor) | regulates a cell's passage past the G2 checkpoint into the M phase; mitosis doesn't start until there is enough MDF and it is later degraded at the end of the M phase |
| The cell cycle clock consists of... | cyclins and cyclin-dependent kinases (CDK) |
| G1 Checkpoint | checks for cell size, nutrients, growth factors, and DNA damage |
| G2 Checkpoint | checks for cell size and proper DNA replication |
| Spindle Assembly Checkpoint | checks for chromosome attachment to spindles |
| Living organisms are distinguished by their ability to... | reproduce their own kind |
| Genetics | the scientific study of heredity and variation |
| Variation | demonstrated by the differences in appearance that offspring show from parents and siblings |
| Heredity | the transmission of traits from one generation to the next |
| Offspring acquire genes from their parents by inheriting... | chromosomes |
| How are genes passed to the next generation? | reproductive cells (germ cells) which produce gametes (sperm and egg) |
| Life Cycle | how we go from gametes to living, reproducing organisms |
| Two types of reproduction | asexual and sexual |
| Asexual Reproduction | reproduction by one parent through either binary fission or budding which makes an exact copy of the parent |
| Sexual Reproduction | produces gametes that increase genetic variation |
| Fertilization | the union of sperm and egg |
| Zygote | a fertilized egg; diploid cell produced by the union of haploid gametes that will grow via mitosis |
| Diploid Cell | (2n) has two sets of chromosomes |
| Human diploid number | 46 (2n=46) |
| Haploid Cell | (n) has one set of chromosomes |
| Human haploid number | 23 (n=23) |
| Which cells can divide by mitosis? | haploid or diploid cells |
| Which cells can undergo meiosis? | only diploid cells |
| DNA replication in mitosis and meiosis occurs when? | in interphase |
| Number of divisions in mitosis | 1 |
| Number of divisions in meiosis | 2 |
| Number of daughter cells and genetic composition in mitosis | Two, each diploid (2n) and genetically identical to the parent cell |
| Number of daughter cells and genetic composition in meiosis | Four, each haploid (n), containing half as many chromosomes as the parent cell; genetically different from the parent cell and from each other |
| Meiosis I | homologous chromosomes pair up and separate, resulting in 2 haploid daughter cells with replicated chromosomes |
| Meiosis II | sister chromatids separate |
| 4 phases of meiosis I and II | prophase, metaphase, anaphase, telophase/cytokinesis |
| What stage of meiosis is most similar to mitosis? | meiosis II |
| What phase of meiosis typically takes up 90% of the time? | prophase I |
| Prophase I | each pair of chromosomes form a tetrad (four chromatids together), each tetrad usually has one or more regions where crossing over occurs |
| Crossing over | when homologous chromosomes (non-sister chromatids) exchange segments of DNA in prophase I (increases variation) |
| What does crossing over create? | recombinant chromosomes (combines DNA from both parents into one chromosome) |
| Metaphase I | microtubules from one pole are attached to the kinetochore of one chromosome of each tetrad and lines them up in the middle of the cell |
| Anaphase I | one chromosome from each tetrad moves towards each pole, homologous chromosomes separate, sister chromatids stay together |
| Telophase I and Cytokinesis | cleavage furrow forms making two haploid daughter cells |
| Difference between plants and animals in cytokinesis | animals- a cleavage furrow forms; plants- a cell plate forms |
| When does the cell become haploid in meiosis? | meiosis I |
| Prophase II | 2 cells coming from telophase/cytokinesis, mitotic spindle forms, nuclear envelope fragments, and chromosomes condense |
| Metaphase II | microtubules attach to the kinetochores of sister chromatids and line them up in the middle of the cell |
| Anaphase II | sister chromatids separate and move to opposite poles of the cell |
| Telophase II/ Cytokinesis | cytokinesis separates the cytoplasm again forming four cells (two cells split) |
| Three mechanisms that contribute to genetic variation: | crossing-over, independent assortment of chromosomes, random fertilization |
| The information content of DNA is in the form of... | specific sequences of nucleotides |
| The DNA inherited by an organism leads to specific traits by... | dictating the synthesis of proteins |
| What is the link between genotype and phenotype? | proteins |
| Gene expression | the process by which DNA directs protein synthesis |
| Genotype | genetic makeup |
| Phenotype | physical appearance or function |
| Does DNA leave the nucleus? | no |
| Two stages to make a protein using the information in DNA: | transcription and translation |
| Transcription | the synthesis of RNA using DNA as a template |
| Translation | the synthesis of a polypeptide (protein) using mRNA as a template |
| 3 types of RNA | mRNA, rRNA, tRNA |
| Messenger RNA (mRNA) | transcribes the directions to make a protein through protein synthesis that are in DNA |
| In what direction does mRNA transcribe DNA? | 5' to 3' |
| Ribosomal RNA (rRNA) | found in ribosomes |
| What makes up a ribosome? | rRNA and a protein |
| Ribosome | site of protein synthesis by the process of translation |
| Transfer RNA (tRNA) | picks up a specific amino acid and carries it to the ribosome, where tRNA recognizes the appropriate codon in the mRNA |
| tRNA structure | held together by hydrogen bonds, has anti-codon loops containing a codon which pairs with the mRNA codon during translation (runs 3' to 5'), also carries a specific amino acid on the other end |
| Where are codons found? | on mRNA |
| First stage of gene expression | transcription |
| Molecular components of transcription | promoter, transcription factors, and RNA polymerase |
| Transcription factor | a regulatory protein that binds to DNA and affects transcription of specific genes |
| Three stages of transcription and translation | initiation, elongation, and termination |
| Initiation (transcription) | complex forms, RNA polymerase binds to DNA |
| Elongation (transcription) | RNA polymerase adds RNA nucleotides to make a new mRNA molecule. Sequence is complementary to the template strand |
| Termination (transcription) | RNA polymerase is released form the template strand. Completed RNA transcript |
| Base change in RNA | uracil instead of thymine (a now pairs with u) |
| Modifications of a pre-mRNA molecule | 5' end has a 5' cap which carries phosphates to provide energy and the 3' end has a poly-A tail which is a sequence of nucleotides that prevents erosion |
| Functions of the modifications of a pre-mRNA molecule | facilitate the export of mRNA, protect mRNA from hydrolytic enzymes, and help ribosomes attach to the 5' end |
| RNA splicing consists of... | snurps (snRNP's) and spliceosomes |
| Snurps (snRNP's) | flag areas that are non-coding to be spliced |
| Spliceosome | cuts out non-coding areas flagged by snurps on the mRNA |
| RNA splicing removes____ and joins _____ | introns, exons |
| Introns | noncoding regions that are spliced out of mRNA |
| Exons | coding regions that leave the nucleus in the proofread mRNA; portions of sequence that will be expressed |
| Genetic information flows from mRNA to protein through which process? | translation |
| Molecular components of translation | mRNA, tRNA, and ribosomes |
| Why are molecules of tRNA not identical? | each tRNA carries a specific amino acid on one end called a free amino acid |
| Three binding sites for tRNA on a ribosome | P site, A site, E site |
| How are the sites on a ribosome read? | APE |
| P site | growing polypeptide site |
| A site | where the amino acid comes in; tRNA transfers in a free amino acid based on a codon in mRNA |
| E site | emptied tRNA exits |
| Initiation (translation) | brings together mRNA, a tRNA with the first amino acid, and the two ribosomal subunits |
| Termination (translation) | occurs when a stop codon in mRNA reaches the A site of the ribosome |
| According to Beadle and Tatum's hypothesis, how many genes are necessary for a simple metabolic pathway? | 2 |
| What enzyme catalyzes the attachment of an amino acid to tRNA? | aminoacyl-tRNA synthetase |
| The tRNA anticodon, GAC, is complementary to the mRNA codon with the sequence _____. | CUG |
| The initiator tRNA attaches at the ribosome's _____ site. | P |
| What name is given to the process in which a strand of DNA is used as a template for the manufacture of a strand of pre-mRNA? | transcription |
| What name is given to the process in which the information encoded in a strand of mRNA is used to construct a protein? | translation |
| What name is given to the process in which pre-mRNA is edited into mRNA? | RNA processing |
| Polypeptides are assembled from... | amino acids |
| RNA processing converts the RNA transcript into... | mRNA |
| What is the process called that converts the genetic information stored in DNA to an RNA copy? | transcription |
| DNA does not store the information to synthesize which of the following? -Organelles -mRNA -Proteins -DNA | Organelles |
| Promoter | a site in DNA where RNA polymerase must bind to initiate transcription; regulatory region of a protein-coding gene |
| What determines which base is to be added to an RNA strand during transcription? | Base pairing between the DNA template strand and the RNA nucleotides |
| Which of the following terms best describes the relationship between the newly synthesized RNA molecule and the DNA template strand? | Complementary |
| What happens to RNA polymerase II after it has completed transcription of a gene? | It is free to bind to another promoter and begin transcription |
| The genetic code is essentially the same for all organisms. From this, one can logically assume... | a gene from an organism can theoretically be expressed by any other organism |
| Building blocks of proteins | amino acids |
| What is the polymer called that is made up of monomers that is specific to a protein? | polypeptide |
| What is the bond called between the monomers of the growing polymer? | peptide bond |
| Where is the site of protein reproduction in a cell? | ribosome |
| How does the cell know what protein to produce? Where is the information stored? | tRNA brings in a free amino acid which matches up with the codon on mRNA |
| How is nucleic acid and a protein connected? | The sequence of the codons in nucleic acids determines the sequence of amino acids in a protein |
| What RNA has the codon? | mRNA |
| What is an anti-codon and what RNA has it? | An anti-codon matches up with the codon and decodes mRNA during protein synthesis. tRNA has the anti-codon |
| Does an anti-codon or a codon determine what amino acid it is? | anti-codon |
| What is the directionality of a DNA template strand? | 3' to 5' |
| Wobble base | flexible pairing at the third base of a codon that allows some tRNAs to bind to more than one codon (ex. AUU, AUC, and AUA, all code for Ilc) |
| Mutations | changes in the genetic material of a cell |
| Point mutations | a type of missense mutation where there is a change in just one base pair of a gene |
| Silent mutations | has no effect on the amino acid produced by a codon because of redundancy in the genetic code |
| Missense mutations | can affect one or more bases causing coding for an incorrect amino acid |
| Nonsense mutations | changes an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein |
| What number and types of chromosomes are found in a human somatic cell? | 44 autosomes and 2 sex chromosomes |
| How do homologous chromosomes and sister chromatids differ from each other? | Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. |
| When does synapsis occur? | prophase I |
| During _____ chromosomes align single file along the equator of a haploid cell. | metaphase II |
| During _____ both the contents of the nucleus and the cytoplasm are divided. | the mitotic phase |
| During _____ the cell grows and replicates both its organelles and its chromosomes. | interphase |
| Nucleoli are present during... | interphase |
| Which of the following results when homologous chromosomes cross over in meiosis? | Corresponding segments of non-sister chromatids are exchanged |
Created by:
kkade
Popular Biology sets