Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 40m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 20m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 52m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 57m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

29. Fungi

Fungi

General Biology

29. Fungi

Fungi

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2:29 minutes

Problem 2`

Textbook Question

After S phase, what makes up a single chromosome?
a. Two daughter chromosomes
b. A double-stranded DNA molecule
c. Two single-stranded DNA molecules
d. Two sister chromatids

Verified step by step guidance

Understand the context of the S phase in the cell cycle. The S phase, or synthesis phase, is the part of the cell cycle in which DNA replication occurs, resulting in the duplication of the cell's genetic material.

Recognize that after the S phase, each chromosome consists of two identical copies of DNA. These copies are known as sister chromatids.

Recall that a single chromosome before the S phase is made up of one double-stranded DNA molecule. After the S phase, this molecule is replicated, forming two identical double-stranded DNA molecules.

Identify that these two identical double-stranded DNA molecules are held together at a region called the centromere, forming what is known as sister chromatids.

Conclude that after the S phase, a single chromosome is composed of two sister chromatids, which are identical copies of the original chromosome.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

S Phase of the Cell Cycle

The S phase, or synthesis phase, is a part of the cell cycle where DNA replication occurs. During this phase, each chromosome is duplicated, resulting in two identical copies called sister chromatids. These chromatids are crucial for ensuring that each daughter cell receives an exact copy of the genetic material during cell division.

Chromosome Structure

A chromosome is a long DNA molecule with part or all of the genetic material of an organism. After the S phase, each chromosome consists of two sister chromatids, which are identical copies of the original chromosome. These chromatids are joined together at a region called the centromere, forming the characteristic X-shape seen during cell division.

Sister Chromatids

Sister chromatids are the two identical halves of a duplicated chromosome, formed during the S phase of the cell cycle. They are connected by a centromere and are eventually separated during mitosis or meiosis to ensure that each daughter cell receives an identical set of chromosomes. This duplication and separation are essential for genetic consistency across cell generations.