Cell Biology - Biology
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Which of the following organelles is found in plant cells, but not in animal cells?
Which of the following organelles is found in plant cells, but not in animal cells?
Plant cells are very similar to animal cells, but receive energy from sunlight. As a result, they require chloroplasts in order to house the chlorophyll where photosynthesis takes place. Animal cells are incapable of photosynthesis, and do not contain chloroplasts.
The other listed structures are found in both animal and plant cells.
Plant cells are very similar to animal cells, but receive energy from sunlight. As a result, they require chloroplasts in order to house the chlorophyll where photosynthesis takes place. Animal cells are incapable of photosynthesis, and do not contain chloroplasts.
The other listed structures are found in both animal and plant cells.
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The nucleolus .
The nucleolus .
The nucleolus is a subdivision of the nucleus; thus, it is only found in eukaryotes. It is the site of ribosome assembly. The nucleolus is made of RNA and proteins.
The nucleolus is a subdivision of the nucleus; thus, it is only found in eukaryotes. It is the site of ribosome assembly. The nucleolus is made of RNA and proteins.
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In the chemical reaction of photosynthesis, photoautotrophs combine carbon dioxide and water to produce sugar and which of the following?
In the chemical reaction of photosynthesis, photoautotrophs combine carbon dioxide and water to produce sugar and which of the following?
Sugar (glucose) and oxygen are the two products of photosynthesis. Methane is a gas consisting of carbon and hydrogen. ATP is the energy produced in the organelle mitochondria. Ethyl alcohol is the active substance in beer and wine that causes intoxication if too much is consumed.
Sugar (glucose) and oxygen are the two products of photosynthesis. Methane is a gas consisting of carbon and hydrogen. ATP is the energy produced in the organelle mitochondria. Ethyl alcohol is the active substance in beer and wine that causes intoxication if too much is consumed.
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Prior to the onset of menstruation, the development of primary oocytes is paused in what phase of meiosis?
Prior to the onset of menstruation, the development of primary oocytes is paused in what phase of meiosis?
Primary oocytes enter meiosis I and replicate their genomes, but they do not make their first meiotic division. They remain in prophase I until a female begins her first menstrual cycle. Then, each month, one primary oocyte resumes the process of meiotic division.
Primary oocytes enter meiosis I and replicate their genomes, but they do not make their first meiotic division. They remain in prophase I until a female begins her first menstrual cycle. Then, each month, one primary oocyte resumes the process of meiotic division.
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Where does fertilization of the ovum typically occur?
Where does fertilization of the ovum typically occur?
Fertilization typically occurs in the fallopian tube. After fertilization, the diploid zygote will begin the process of implantation into the uterus, where it undergoes mitotic divisions. The resulting multicellular organism is called the embryo, which further develops in the uterus into a fetus.
Fertilization typically occurs in the fallopian tube. After fertilization, the diploid zygote will begin the process of implantation into the uterus, where it undergoes mitotic divisions. The resulting multicellular organism is called the embryo, which further develops in the uterus into a fetus.
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Most cells spend the vast majority of their time in .
Most cells spend the vast majority of their time in .
Most cells spend about 90% of their time in interphase. Note that mitosis and meiosis comprise only about 10% of the cell cycle.
Most cells spend about 90% of their time in interphase. Note that mitosis and meiosis comprise only about 10% of the cell cycle.
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Out of all phases in the cell cycle, most cells spend the majority of their life in .
Out of all phases in the cell cycle, most cells spend the majority of their life in .
Cell division, or mitosis, is a rather small portion of a cell's life and includes prophase, metaphase, anaphase and telophase. The majority of a cell's life is spent in interphase.
Cell division, or mitosis, is a rather small portion of a cell's life and includes prophase, metaphase, anaphase and telophase. The majority of a cell's life is spent in interphase.
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DNA replication occurs during which of the following phases of the cell cycle?
DNA replication occurs during which of the following phases of the cell cycle?
DNA is synthesized in the S phase only. The G phases are stages of cellular growth while the M phase consists of mitotic cellular division.
DNA is synthesized in the S phase only. The G phases are stages of cellular growth while the M phase consists of mitotic cellular division.
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During what phase of mitosis does the cell physically split into two daughter cells?
During what phase of mitosis does the cell physically split into two daughter cells?
The cell cycle consists of four major phases: G1, S, G2, and M.
The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis.
Prophase is when the nuclear envelope dissolves and chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell by spindle fibers. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.
It is important to note that the cell generates two daughter nuclei during telophase, but the cytoplasm does not divide until cytokinesis. As such, there is a short period during which the cell has two, identical, fully formed nuclei.
The S phase of the cell cycle is the period during which DNA is replicated.
The cell cycle consists of four major phases: G1, S, G2, and M.
The M phase is mitosis, which is further broken down into prophase, metaphase, anaphase, telophase, and cytokinesis.
Prophase is when the nuclear envelope dissolves and chromosomes condense. Metaphase is when the chromosomes line up at the metaphase plate in the center of the cell. Anaphase is when the sister chromatids are pulled to opposite sides of the cell by spindle fibers. Telophase is when the cell begins to split and the nuclear membrane reassembles. Cytokinesis is when the cytoplasm pinches off and two daughter cells are formed.
It is important to note that the cell generates two daughter nuclei during telophase, but the cytoplasm does not divide until cytokinesis. As such, there is a short period during which the cell has two, identical, fully formed nuclei.
The S phase of the cell cycle is the period during which DNA is replicated.
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How is mitochondrial DNA (mDNA) different from nuclear DNA?
How is mitochondrial DNA (mDNA) different from nuclear DNA?
Mitochondrial DNA is much smaller and simpler than nuclear DNA, meaning it does not need histones or introns. Mitochondrial DNA is also circular, like bacterial DNA, rather than linear like nuclear DNA. As the ovum is the only contributor of mitochondria to an offspring, all mDNA must therefore be inherited from the mother.
Mitochondrial DNA is much smaller and simpler than nuclear DNA, meaning it does not need histones or introns. Mitochondrial DNA is also circular, like bacterial DNA, rather than linear like nuclear DNA. As the ovum is the only contributor of mitochondria to an offspring, all mDNA must therefore be inherited from the mother.
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Where does spermatogenesis occur?
Where does spermatogenesis occur?
Spermatogenesis is the process of producing the male gametes, spermatozoa (sperm). The spermatogonia in the seminiferous tubules of the testes mature into spermatocytes, which undergo meiosis to form spermatozoa. The spermatozoa complete their maturation process in the epididymas, then they are ready to enter the vas deferens before ejaculation. Lumen is a general term that means "an opening." Although spermatogenesis does occur in the lumen of the seminiferous tubules, the term lumen is too broad and is not the best answer. An ampulla is a general term that, in anatomy, means "the dilated end of a duct." There is an ampulla of the vas deferens before it enters the prostate gland, but spermatogenesis does not occur there. The prostate gland produces a milky, alkaline solution that comprises about 30% of semen. The seminal vesicles are glands that produce the majority of the solution that will become semen. Note the difference between semen (fluid) and sperm (cells).
Spermatogenesis is the process of producing the male gametes, spermatozoa (sperm). The spermatogonia in the seminiferous tubules of the testes mature into spermatocytes, which undergo meiosis to form spermatozoa. The spermatozoa complete their maturation process in the epididymas, then they are ready to enter the vas deferens before ejaculation. Lumen is a general term that means "an opening." Although spermatogenesis does occur in the lumen of the seminiferous tubules, the term lumen is too broad and is not the best answer. An ampulla is a general term that, in anatomy, means "the dilated end of a duct." There is an ampulla of the vas deferens before it enters the prostate gland, but spermatogenesis does not occur there. The prostate gland produces a milky, alkaline solution that comprises about 30% of semen. The seminal vesicles are glands that produce the majority of the solution that will become semen. Note the difference between semen (fluid) and sperm (cells).
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What is the "powerhouse" of the cell?
What is the "powerhouse" of the cell?
The mitochondria is responsible for making the energy for the cell by cellular respiration. It does this by taking the major breakdown products of glucose (pyruvate and NADH) and converting them into ATP by the citric acid cycle and electron transport chain. This is an oxygen-dependent process.
The mitochondria is responsible for making the energy for the cell by cellular respiration. It does this by taking the major breakdown products of glucose (pyruvate and NADH) and converting them into ATP by the citric acid cycle and electron transport chain. This is an oxygen-dependent process.
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Which of the following organelles has only one membrane?
Which of the following organelles has only one membrane?
Lysosomes are specialized vesicles that bud off of the Golgi apparatus and house digestive enzymes within the cell. Lysosomes have only one outer membrane, made of a phospholipid bilayer, similar to the plasma membrane surrounding the cell.
In contrast, the nucleus, mitochondria, and chloroplasts all have two outer membranes. Each of these is made of a lipid bilayer, for a total of four layers of phospholipids around these structures.
Lysosomes are specialized vesicles that bud off of the Golgi apparatus and house digestive enzymes within the cell. Lysosomes have only one outer membrane, made of a phospholipid bilayer, similar to the plasma membrane surrounding the cell.
In contrast, the nucleus, mitochondria, and chloroplasts all have two outer membranes. Each of these is made of a lipid bilayer, for a total of four layers of phospholipids around these structures.
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Which event takes place during anaphase II?
Which event takes place during anaphase II?
During prophase I, homologous chromosomes form tetrads along the center of the cell. Full chromosomes are pulled to each pole during anaphase I, resulting in two haploid cells at the end of meiosis I. During prophase II, sister chromatids align at the center of the cell in singular chromosome structures. These sister chromatids are separated during anaphase II, resulting in a total of four haploid cells.
During prophase I, homologous chromosomes form tetrads along the center of the cell. Full chromosomes are pulled to each pole during anaphase I, resulting in two haploid cells at the end of meiosis I. During prophase II, sister chromatids align at the center of the cell in singular chromosome structures. These sister chromatids are separated during anaphase II, resulting in a total of four haploid cells.
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Which structures are responsible for breaking down proteins, nucleic acids, lipids, and carbohydrates?
Which structures are responsible for breaking down proteins, nucleic acids, lipids, and carbohydrates?
Lysosomes are membrane-bound organelles that contain digestive enzymes which break down all four types of macromolecules. The mitochondria is responsible for synthesis of the majority of the cell's energy in the form of ATP. The cytoskeleton maintains cell shape and provides a "freeway" for transporting substances within the cell. Flagella are proteinaceous structures that aid in cell motility.
Lysosomes are membrane-bound organelles that contain digestive enzymes which break down all four types of macromolecules. The mitochondria is responsible for synthesis of the majority of the cell's energy in the form of ATP. The cytoskeleton maintains cell shape and provides a "freeway" for transporting substances within the cell. Flagella are proteinaceous structures that aid in cell motility.
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What is the first stage of meiosis during which a cell is considered haploid?
What is the first stage of meiosis during which a cell is considered haploid?
A diploid cell will have two copies of each chromosome, known as a homologous pair. A haploid cell will only have one copy of each chromosome, though the chromosome may consist of two sister chromatids.
Diploid cell: (XX)
Haploid cell: (X)
During meiosis I, the cell is diploid because the homologous chromosomes are still located within the same cell membrane. Only after the first cytokinesis, when the daughter cells of meiosis I are fully separated, are the cells considered haploid. Following this first division, the cell begins meiosis II with prophase II, making this the first haploid meiotic stage.
A diploid cell will have two copies of each chromosome, known as a homologous pair. A haploid cell will only have one copy of each chromosome, though the chromosome may consist of two sister chromatids.
Diploid cell: (XX)
Haploid cell: (X)
During meiosis I, the cell is diploid because the homologous chromosomes are still located within the same cell membrane. Only after the first cytokinesis, when the daughter cells of meiosis I are fully separated, are the cells considered haploid. Following this first division, the cell begins meiosis II with prophase II, making this the first haploid meiotic stage.
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What occurs during the S phase of the cell cycle?
What occurs during the S phase of the cell cycle?
The S phase occurs between the G1 and G2 phases and is the stage during which DNA is replicated, and then checked for defects. Depending on the level of nutrients and energy available, the cell will either enter the G0 phase or the M phase.
During the G1 phase, the cell replicates organelles and grows in size. During the G2 phase, DNA is checked for damage and the cell prepares to divide. The M phase refers to mitosis, while the G0 phase refers to quiescence—a period during which the cell is not preparing for division.
The S phase occurs between the G1 and G2 phases and is the stage during which DNA is replicated, and then checked for defects. Depending on the level of nutrients and energy available, the cell will either enter the G0 phase or the M phase.
During the G1 phase, the cell replicates organelles and grows in size. During the G2 phase, DNA is checked for damage and the cell prepares to divide. The M phase refers to mitosis, while the G0 phase refers to quiescence—a period during which the cell is not preparing for division.
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Which three events most accurately describes what occurs in meiosis I?
Which three events most accurately describes what occurs in meiosis I?
In meiosis I, the homologous chromosomes have already been duplicated in S phase of interphase. The sister chromatids are identical at this stage. Homologous chromosomes pair in prophase I, forming tetrads. The tetrads then cross over, exchanging genetic material. Then, the genetically-mixed tetrads line up on the metaphase plate and are separated in anaphase I. Note that after the first meiotic division, the two daughter cells are nonidentical and are haploid.
In meiosis I, the homologous chromosomes have already been duplicated in S phase of interphase. The sister chromatids are identical at this stage. Homologous chromosomes pair in prophase I, forming tetrads. The tetrads then cross over, exchanging genetic material. Then, the genetically-mixed tetrads line up on the metaphase plate and are separated in anaphase I. Note that after the first meiotic division, the two daughter cells are nonidentical and are haploid.
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What is responsible for the movement of proteins, RNA, and other specific molecules into and out of the nucleus?
What is responsible for the movement of proteins, RNA, and other specific molecules into and out of the nucleus?
Nuclear pores are complex structures made up of proteins which allow movement of certain molecules into and out of the nucleus. Flagella are long tail-like projections found on some cells that function in cell motility. The rough endoplasmic reticulum has ribosomes on it, which are the sites of protein synthesis. Lysosomes are organelles that contain hydrolytic enzymes used to recycle/destroy macromolecules.
Nuclear pores are complex structures made up of proteins which allow movement of certain molecules into and out of the nucleus. Flagella are long tail-like projections found on some cells that function in cell motility. The rough endoplasmic reticulum has ribosomes on it, which are the sites of protein synthesis. Lysosomes are organelles that contain hydrolytic enzymes used to recycle/destroy macromolecules.
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During which phase of meiosis does DNA begin to condense?
During which phase of meiosis does DNA begin to condense?
Mitosis is also known as "karyokinesis." "Karyo-" refers to the nucleus. (Remember that eu-KARY-ote means true ("eu-") nucleus, and pro-KARY-ote means before ("pro-") nucleus.) The "-kinesis" part of "karyokinesis" comes from the same roots as "kinetic" and refers to movement. Thus, mitosis is the movement of the nucleus. Packing of the DNA occurs in prophase of mitosis so that it's easier to move rather than having to move the loose chromatin. Think of moving forty-six strands of hundreds of yards of yarn—we would want it to be tightly coiled to make it manageable.
Mitosis is also known as "karyokinesis." "Karyo-" refers to the nucleus. (Remember that eu-KARY-ote means true ("eu-") nucleus, and pro-KARY-ote means before ("pro-") nucleus.) The "-kinesis" part of "karyokinesis" comes from the same roots as "kinetic" and refers to movement. Thus, mitosis is the movement of the nucleus. Packing of the DNA occurs in prophase of mitosis so that it's easier to move rather than having to move the loose chromatin. Think of moving forty-six strands of hundreds of yards of yarn—we would want it to be tightly coiled to make it manageable.
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