Biology Test 4 PDF

‫בס״ד‬ Please don’t delete the comments I wrote AI Podcast based on the Study Guide AI Video (very short) Test 4 - Thursday February 13, 2025 - Asexual and Sexual Reproduction, Cell cycle and Mitosis, DNA, DNA Replication and...

‫בס״ד‬ Please don’t delete the comments I wrote AI Podcast based on the Study Guide AI Video (very short) Test 4 - Thursday February 13, 2025 - Asexual and Sexual Reproduction, Cell cycle and Mitosis, DNA, DNA Replication and Protein Synthesis ​Sexual and Asexual Reproduction- ( Amoeba Sisters Video ) ​ Be able to explain the differences between asexual and sexual reproduction. -Asexual Reproduction: offspring have some DNA as their one parent (clones). Seen in bacteria, some plants, and many invertebrate animals. -Sexual Reproduction: involves mating. Offspring are different from their parents, they are unique!! Seen in most animals and plants. Most common form of reproduction. Cells from both parents combine! 2 gametes unite to make a zygote. -Sperm -Egg ○​ Be able to describe the advantages and disadvantages of each. -Asexual- Advantages: can make offspring faster. Don’t need to find a partner. Disadvantages: all genetically identical. Species can’t change and adapt. One disease can wipe out a whole population. -Sexual- Advantages: variation (differences) !!! Species can adopt. Disadvantages: takes more time. Need to find a partner. Offspring only gets half of parents’ DNA (individual disadvantage). ○​ Be able to determine the type of reproduction if given a new example. ​CELL CYCLE AND MITOSIS (Amoeba Sisters Video ) ​ Why do multicellular organisms undergo cell division to make new cells? -So we can grow, repair our wounds, so we can replace older dead cells, reproduce and fight infection.  ‫בס״ד‬ ​ What occurs during the different stages of the cell cycle (3 parts of interphase and mitosis/cytokinesis) -G1- grows until it doubles in size. Makes new proteins and organelles that it needs to carry out its functions. Cell is living its normal life! -S phase- DNA synthesis. Chromosomes are replicated and after that each chromosome consists of 2 identical “sister” chromatids, which are attached at an area called the centromere. And then when the cell divides, the chromatids separate, so each new cell will get one chromatid. -G2 (second gap phase)- organelles and molecules required for cell division are produced. It's the preparation for mitosis. And it checks the cell for mistakes. MITOSIS- DIVISION OF THE CELL NUCLEUS -Prophase- chromosomes condense from chromatin to condensed chromosomes and become visible. The centrioles move to opposite poles and the spindle fibers begin to form (spindle fibers made of microtubules). The nuclear envelope begins to break down. -Metaphase- spindle fibers attach to the sister chromatids at the kinetochore region. Chromosomes line up single-file at the center of the cell. -Anaphase- cell elongates. Microtubules shorten. Sister chromatids pull apart and move toward opposite sides. -Telophase- 2 new nuclear envelopes form around the chromosomes. Spindle fibers disintegrate. The chromosomes decondense to form chromatin. CYTOKINESIS- DIVISION OF THE CYTOPLASM -​ In animal cells, the cell membrane pinches in the center to form 2 daughter cells. Now we have 2 identical daughter cells, each with an identical set of DNA. In plants, a structure known as the cell plate forms midway between the divided nuclei. ​ How long does interphase take (approximately) compared to mitosis/cytokinesis? -​ Interphase takes up most of the cell’s life, compared to mitosis that’s really fast. ​ What occurs during the different stages of mitosis? Be able to recognize how the cell and chromosomes would look in the cell during the different stages. -Prophase- chromosomes condense from chromatin to condensed chromosomes and become visible. The centrioles move to opposite poles and the spindle fibers begin to form (spindle fibers made of microtubules). The nuclear envelope begins to break down. -Metaphase- spindle fibers attach to the sister chromatids at the kinetochore region. Chromosomes line up single-file at the center of the cell. -Anaphase- cell elongates. Microtubules shorten. Sister chromatids pull apart and move toward opposite sides. -Telophase- 2 new nuclear envelopes form around the chromosomes. Spindle fibers disintegrate. The chromosomes decondense to form chromatin.  ‫בס״ד‬ ​ Be able to draw each of the phases of mitosis including what the chromosomes look like in each phase ​ What is the difference in the way plant and animal cells divide by cytokinesis? -In animal cells, the cell membrane pinches in the center to form 2 daughter cells. Now we have 2 identical daughter cells, each with an identical set of DNA. In plants, a structure known as the cell plate forms midway between the divided nuclei. ​ In mitosis, how do the daughter cells compare to parent cell? -​ They are identical. ​ How is the cell cycle regulated? (3 checkpoints and G0) -​ Cells make decisions throughout the cell cycle about whether or not to proceed with cell division. They won’t divide if conditions inside and outside the cell aren’t right. (Ex: when there isn’t enough space around or if DNA is damaged. -​ G1- At the end of G1, before S phase. Commitment to divide or not. If a cell moves through here, it will almost certainly divide. (Checks for: cell size, nutrient, growth factors, and DNA damage). -​ G0 phase- if a cell decides not to divide again, it will enter G0. Cells may later resume the cell cycle. Some cells stay in G0 forever!! They carry on performing their normal functions but will never divide. (Ex: muscle and brain cells). -​ G2- At the end of G2 before mitosis. Cell will check if DNA is damaged and if it was copied completely during the S phase. May pause here to allow for repairs or undergo apoptosis. -​ Mitosis checkpoint- In between metaphase and anaphase. Checks to ensure that all the sister chromatids are attached to the spindle at the metaphase plate. APC= anaphase- promoting complex. ○​ What can happen when regulation fails? -​ Cancer (uncontrolled cell division).  ‫בס״ד‬ ​DNA ​ What type of macromolecule is DNA? What is the monomer? -​ Macromolecule- nucleic acids. Monomer- nucleotides. ​ What elements make up DNA? -​ C, H, O, N, P. ( Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus ). ​ What are the components of a nucleotide? Be able to draw and label a nucleotide. -​ 5- carbon sugar- deoxyribose or ribose. -​ Nitrogenous base. -​ Phosphate group. -​ [A]=[T] and [C]=[G].🍎➡️🌳 🚗➡️🏠 ​ What is Chargaff’s rule and what is its significance? , ​ Be able to determine what percentage of DNA is A, T, C or G based on one given amount. -​ A=T, C=G ​ What is the function of DNA? -​ Store our genetic information, code for our traits (proteins). ​ Where in the cell is DNA located? -​ Cell nucleus. ​ Review the structure of DNA. Know what makes up the backbone and rungs of the double helix. -​ 2 strands of DNA are held together by hydrogen bonds between bases.  ‫בס״ד‬ -​ DNA has a sugar-phosphate backbone made of alternating deoxyribose and phosphates. -​ The bases in the middle of the DNA molecule are attached to their pairs by hydrogen bondings=rungs. ​ What is meant by “complementary base pairing” and “antiparallel”? ​ Be able to place in size order: gene, nucleus, nucleotide, chromatid, chromosome -​ (Smallest) nucleotide, gene, chromatid, chromosome, nucleus. (Largest) ​ Know that hydrogen bonds are the weak bonds that connect the two strands of DNA ​DNA Replication ( Amoeba Sisters Video ) ​ Why do we need to replicate our DNA? -​ So the 2 daughter cells will have the exact identical set of DNA as the parents cell. ​ Be able to explain the steps of DNA replication. -​ Step 1- An enzyme called HELICASE unwinds the double helix, it “unzips” the 2 DNA strands by breaking the weak hydrogen bonds between the base pairs. -​ Step 2- An enzyme called DNA POLYMERASE adds new nucleotides to the open original DNA strand by base pairing to synthesize a new, complementary strand of DNA for each original strand. Each strand from the original DNA molecule serves as a template for the new complementary strands. -​ Step 3- An enzyme called LIGASE connects the Okazaki fragments in the lagging strand. -​ Done!- At the end of replication, there are 2 molecules of DNA which are exact copies of each other. Each DNA molecule is half old and half new. (Semi-conservative Replication). ​ What do the enzymes Helicase, DNA polymerase, and Ligase do? -Helicase- unwinds the double helix, it “unzips” the 2 DNA strands by breaking the weak hydrogen bonds between the base pairs. -DNA polymerase- adds new nucleotides to the open original DNA strand by base pairing to synthesize a new, complementary strand of DNA for each original strand.  ‫בס״ד‬ Each strand from the original DNA molecule serves as a template for the new complementary strands. -Ligase- “glue”, connects the Okazaki fragments in the lagging strand. ​ What is a replication fork? -​ The area where the 2 strands are being separated. (like a zipper in a zip up hoodie). ​ Make sure to know that DNA polymerase can only synthesize DNA in the 5’ to 3’ direction. Make sure that you understand what issue this presents during the process of replication. -​ Because the Lagging strand makes the strands in SHORT pieces, compared to the leading strand that makes the strands CONTINUOUSLY. ​ Why is one strand considered the leading strand and the other the lagging strand? Be able to identify which strand is which if given a diagram of replication. -​ Leading Strand- is the strand of newly synthesized in the SAME direction as the growing replication fork - CONTINUES replication. -​ Lagging Strand- starts at the replication fork and moves in the OPPOSITE direction. It is DISCONTINUES and occurs in small fragments. ​ What are Okazaki fragments? ​ Why is it considered semiconservative replication? -Semi= half. Conserve- to save. Half of each DNA strand is new, and half is old, kept the same. ​ Be able to draw, label and identify the leading and lagging strands -  ‫בס״ד‬ ​RNA ( Amoeba Sisters video ) ​ What type of macromolecule is RNA? What are monomers? -​ Monomers- nucleotides. Macromolecules- nucleic acids. ​ Review the structure of RNA and its nucleotides. ​ Be able to list the 3 main ways that DNA and RNA differ. -​ The sugar in RNA is ribose instead of deoxyribose. -​ RNA is single-stranded, not double-stranded. -​ RNA contains URACIL in place of Thymine. ​ Know the functions of the 3 types of RNA. -​ mRNA- messenger RNA- carry the code from the gene to the ribosome. -​ tRNA- transfer RNA- carries amino acids to the ribosomes for protein synthesis. -​ rRNA- ribosomal RNA- is what ribosomes are made of. ​PROTEIN SYNTHESIS: ( Amoeba Sisters Video ) ​ Know the 2 main steps of making proteins. -​ The DNA of a gene (a linear sequence of many nucleotides) is transcribed into RNA, which is translated into a peptide. -​ Transcription- the synthesis of mRNA (based on sequence of DNA). Copying a gene from DNA into mRNA so it can leave the nucleus. -​ Translation- the synthesis of proteins (based on sequence of RNA). Using the mRNA code to make a protein. ​ Where in the cell does transcription occur? What is made? -​ Happens in the nucleus, making mRNA. ​ Where in the cell does translation occur? What is made? -​ Happens in the ribosomes in the cytoplasm, makes protein (also known as polypeptide).  ‫בס״ד‬ REMINDER THAT YOU MUST BE PREPARED TO GRAPH AND ANALYZE DATA IN EVERY UNIT!