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
Biol 1406 Exam 4
Meiosis, mitosis, DNA replicaion and Gene expression
| Term | Definition |
|---|---|
| Genome | The complete set of genes in a living organism |
| Chromosomes | Condensed chromatin; called sister chromatids when duplicated |
| Genes | Hereditary information (DNA) passed down from parents |
| Chromatin | DNA wrapped around proteins called histones |
| Somatic Cells | Cells that aren’t gametes; replicate through mitosis |
| Gametes | Sex/germ cells; replicate through meiosis |
| Sister chromatids | Duplicated chromosomes held together by a centromere |
| Centromere | The “narrowed waist” that holds the sister chromatids together |
| Mitosis | Process of cell division |
| Cytokinesis | Division of the cytoplasm |
| How many chromosomes does each somatic cell in our body house? | 46 (2n) |
| How do we inherit our chromosomes? | We receive half from each parent (n) |
| How many chromosomes does a gamete contain? | 23 (n) |
| What is identical between sister chromatids? | Everything; they are genetically identical |
| Where are they attached to each other and what macromolecule facilitates that attachment? | They are attached at the centromere |
| When do sister chromatids become individual chromosomes? | Anaphase (Mitosis) Anaphase II (Meiosis) |
| Does mitosis continue to occur in the human body after birth? If so, in what situation? | Yes, to repair/replace cells and for growth |
| Which phase of the cell cycle is the longest? | Interphase |
| What are the sub-phases of the M phase? Sub-phases of interphase? | M-Phases: Prophase, Metaphase, Anaphase, Telophase Interphase: G1, S, G2 |
| Describe what is happening during the sub-phases of interphase. | G1: Cell prepares to divide through growth and protein and enzyme synthesis S: DNA and organelles duplicated G2: Cytoplasm grows in preparation for division, final checkpoint in interphase before mitosis |
| How many chromosomes are present in a cell in G1 phase? G2 phase? | G1: 46 G2: 46 (92 chromatids) Chromosomes counted by centromere |
| How much DNA is present in a cell during G2 phase in relation to G1 phase? | Double the DNA is present in G2 compared to G1 because the DNA along with the organelles were all doubled in S stage |
| Describe prophase | Chromatin becomes visible and forms sister chromatids, mitotic spindles form, nuclear envelope dissolves |
| Describe metaphase | Mitotic spindles attach to the sister chromatids via the kinetochores on the centromeres and line up the chromatids on the metaphase plate |
| Describe anaphase | Lined up sister chromatids are separated and pulled to opposite ends of the cell by the mitotic spindles |
| Describe telophase | Often overlaps with cytokinesis; cell divides by squeezing the cytoplasm to form a cleavage furrow, nuclear envelope reforms, chromosomes uncoil back into chromatin |
| When does the mitotic spindle begin to form? | Prophase |
| What is the mitotic spindle made of? What structures comprise the mitotic spindle? | Made of centrioles, microtubules, and microfilaments |
| When does the mitotic spindle attach to the kinetochores | Metaphase |
| When does the mitotic spindle pull the separated sister chromatids to opposite sides of the cell | Anaphase |
| When does the mitotic spindle dissolve | Telophase |
| Describe the “tug-of-war” that goes on during metaphase. What is the name of the imaginary plane that the chromosomes align at? | The mitotic spindles attach to the chromosomes and line them up on the metaphase plate |
| What event starts anaphase? | The breaking of the protein cohesion that was holding the sister chromatids together |
| What role do the non-kinetochore microtubules play during anaphase? | The non-kinetochore microtubules get longer, which lengthens the whole cell |
| Describe the process that results in cytokinesis in animal cells. How is this different that the process in plant cells? | Animal cells make a cleavage furrow to start dividing; plants make a cell plate |
| Allele | A type of a gene (Ex: blue eyes or hazel eyes) |
| What are the differences between gametes and somatic cells? | Gametes are sex cells that replicate through meiosis; somatic cells cover the rest of the body and replicate through mitosis |
| Somatic cells are __ ; gametes are __ | diploid; haploid |
| A haploid cell has __ ; a diploid cell has __ | 23 chromosomes (n); 46 chromosomes (2n) |
| Asexual reproduction | Offspring is genetically identical to the parent and is made through mitosis, only one parent is needed |
| Sexual reproduction | Offspring is a genetically random mix of two parents and is produced through meiosis (but once developed grown through mitosis with the exception of the sex cells) |
| Homologous chromosomes | Chromosomes with the same types of genes but not the same specific gene |
| Sex chromosomes | The 23rd pair of chromosomes that are X and Y that determine the human’s sex |
| Autosomes | The first 22 pairs of human chromosomes |
| Diploid cell | Cell with 2 sets of chromosomes (2n; 46 in humans) |
| Haploid cell | Cell with 1 set of chromosomes (n; 23 in humans) |
| Fertilization | Union of haploid sperm and egg cells to form a diploid zygote |
| Zygote | Diploid fertilized egg cell |
| What does the variable n represent when talking about a cell? | Half the number of chromosomes |
| If 2n=8, how many chromosomes would a diploid and haploid cell have? | Diploid: 8 Haploid: 4 |
| If 2n=8, how many homologous pairs of chromosomes would a diploid and haploid cell have? | Diploid: 4 Haploid: 2 |
| A how many chromosomes is a human somatic cell supposed to have? | 46 chromosomes |
| How many chromosomes is a human gamete cell supposed to have? | 23 chromosomes (to make 46 when combined) |
| How many chromosomes is a human zygote cell supposed to have? | 46 chromosomes (half from sperm, half from egg) |
| Meiosis reduces chromosome numbers by half, what process restores chromosome numbers? | Fertilization |
| What are the similarities between mitosis and meiosis? | They take place in the nuclei Result in cell division Occur in the M-phase of the cell cycle Involve DNA synthesis Same names for the stages (PMAT) |
| What are the major events that happen in meiosis that do not occur in mitosis? | Crossing over Double replication (creation of 4 cells) Creation of haploid cells |
| Separation of sister chromatids (meiosis) occurs in | Anaphase II |
| Crossing over occurs in | Prophase I |
| Independent assortment occurs in | Metaphase I |
| What type of cell begins meiosis? | A diploid cell |
| What type and how many cells do we get out of meiosis? | Four haploid cells |
| Define crossing over | When homologous pairs of chromosomes swap parts of their DNA |
| What three things lead to genetic variation in humans? | Independent assortment Random fertilization Crossing over of chromosomes |
| Crossing over of chromosomes occurs in | Prophase I |
| Independent assortment (random pairing of chromosomes) occurs in | Metaphase I |
| Random fertilization occurs | after meiosis |
| Why is genetic diversity important? | It allows more resistance, adaptability, and variation in a species |
| What microorganisms were Hershey and Chase working with? | Bacteriophage (a type of virus) and E. coli |
| What question were Hershey and Chase trying to answer? | Whether DNA or Proteins were the genetic material |
| What DNA and protein characteristics did they use to set up their experiment? | They used radioactive Sulfur (found in proteins but not DNA) and radioactive Phosphorus (found in DNA but not proteins) |
| Would their experiment have worked if they used radio labeled Nitrogen? Why or why not? | No because Nitrogen is found in both DNA and proteins |
| What did Hershey and Chase observe? | That the material the virus injected into the E. coli was marked by the radioactive Phosphorus |
| What conclusion can be made from Hershey and Chase's experiment? | That DNA is the genetic material |
| What are Chargaff's two rules? | Every species differs in its base composition For every A, there is a T. For every C, there is a G |
| The three theories of DNA replication | Conservative Semiconservative Dispersive |
| Conservative | The original DNA helix remained untouched during replication and a 2nd identical helix was created separately |
| Semiconservative | The original helix would separate its DNA strands, and each strand would then be used as a physical template for creating a new, complementary DNA strand. The new helix would be a mix of “old” DNA and “new” DNA |
| Dispersive | The original DNA helix is fragmented and the small pieces serve as a guide for the creation of duplicate pieces, then the fragments somehow reassemble into two new, complete helices |
| How did Meselson and Stahl set up their experiment? | They grew E. coli in N15 (heavier) and N14 (lighter) and placed the N15 E. coli into the N14 E. coli and watched the DNA replicate |
| What did Meselson and Stahl see after 1 round of replication? | 100% were heavy Nitrogen DNA |
| What did Meselson and Stahl see after 2 rounds of replication? | 50% were heavy Nitrogen DNA and 50% were hybrid heavy and light Nitrogen DNA |
| Which theory did Meselson and Stahl’s data support? | Semiconservative DNA replication |
| Origin of replication | place where replication begins |
| Antiparallel | The two DNA strands run opposite to each other |
| 5’ -> 3’ | The direction in which DNA is synthesized 5 carbon sugar to three carbon sugar in the DNA’s backbone |
| Replication fork | The "path" that opens once DNA is unzipped; the two separate open strands the branched DNA at either end of the replication bubble, where new strands are synthesized |
| Leading strand | The top strand that runs 5' -> 3' ; synthesized continuously |
| Lagging strand | The bottom strand that runs 3' -> 5' ; synthesized in fragments by DNA polymerase |
| Okazaki fragment | The fragments that are made when DNA is synthesized on the lagging strand |
| Why does DNA replication only proceed from 5’ -> 3’? | Necessary for repair and energy |
| What steps are needed to fix the lagging strand after it has been made? | RNA primers replaced with DNA and gaps are sealed by ligase |
| Enzymes involved in DNA replication | Primase Helicase DNA polymerase I DNA polymerase III Ligase Topoisomerase Single-strand binding proteins |
| Function of primase | sets down RNA primers to show DNA polymerase where to build DNA |
| Function of helicase | breaks the hydrogen bonds between the DNA bases to 'unzip' the DNA and separate the two helices |
| Function of ligase | Seals the gaps of DNA on the lagging strand after the RNA primers are replaced with DNA |
| Function of topisomerase | Relaxes the DNA strands to keep it from snapping it back together |
| DNA polymerase builds new DNA in | the 5' -> 3' direction |
| Result of DNA replication | 2 DNA molecules, each made of 1 old strand and 1 new strand |
| SSB (single-strand binding) proteins | Hold on to the DNA to keep it from snapping back together |
| Function of DNA polymerase I | Removes RNA nucleotides from the lagging strand and replaces them with DNA |
| Function of DNA polymerase III | Adds DNA to and RNA or pre-existing DNA strand using the old DNA as a template |
| The genetic code is | Redundant Unambiguous Nearly universal Without punctuation |
| one gene–one polypeptide hypothesis recognizes that | some proteins are composed of multiple polypeptides |
| Steps of gene expression | Transcription Translation DNA -> RNA -> proteins |
| What is the genetic code? | the instructions contained in a gene that tell a cell how to make a specific protein |
| What is a codon? Why must a codon be three nucleotides and not one or two? | A codon is a combination of three nucleotides; must be three so there can be enough variety in combinations to have at least one combination for every amino acid |
| How many possible codons exist? How many amino acids? | 64 possible codons for 20 amino acids |
| The DNA strand is the ___ of the mRNA strand | opposite |
| What is the process of transcription? | DNA unzips section RNA polymerase moves down the DNA and makes a copy into mRNA RNA polymerase leaves mRNA left behind and DNA zips back together |
| What enzyme is responsible for carrying out transcription? | RNA polymerase |
| How does the cell know where to begin transcription and where to end transcription? | It starts at the promoter sequence and ends at the terminator sequence |
| What is the process of translation? | The synthesis of proteins under the direction of mRNA |
| What is responsible for carrying out translation? | tRNA |
| Role of tRNA in translation | transfer amino acids from the cytoplasm to the ribosomes for the amino acids to attach to each other and form a polypeptide chain (protein monomer) |
| Role of mRNA in translation | delivers the translated DNA for the tRNA and ribosomes to bond to in order |
| Role of rRNA in translation | Reads the codons and signals for the right tRNA to make the right protein |
| Role of the anticodon in tRNA | allows tRNA to bind to the codon on the mRNA and signal for a specific amino acid |
| Why is it so important that the anticodon and amino acid of a tRNA match according to the genetic code? | If not they could bring the wrong amino acid, which could be disastrous |
| A ribosome is made up of the following sites | P site and A site |
| Function of the P site in a ribosome | The site where the first tRNA binds to |
| Function of the A site in a ribosome | The site where all the other tRNA bind to |
| What happens during translation | mRNA arrives at ribosome Ribosome reads mRNA codons Codons call for specific tRNA with amino acids to make a specific protein Ribosome reads stop codon and stops production |
| Missense mutation | Change in a nucleotide that changes the codon to code for a different amino acid than intended |
| Nonsense mutation | A change in base causes a stop codon to be present prematurely, halting the protein creation sequence |
| Silent mutation | Just one letter changes; does not affect protein formation |
| Frameshift mutation | Insertion or deletion; could shift all the codons after possibly creating totally different proteins with possibly disastrous results |
Created by:
1763
Popular Biology sets