[Growth and reproduction] Introduction to Biology

1. One of the key features that separates life from non-life is: the ability to reproduce

2. Do all cells have the ability to reproduce? yes

3. How do unicellular organisms reproduce? division of one cell reproduces the entire organism

4. What is cell division needed for in multicellular organisms?a. Development of an embryo from a sperm/egg

b. Growth

c. Repair

5. Define asexual reproduction – reproduction that involves a single parent producing an offspring

a. The offspring produced are _in most cases, genetically identical to the single cell that produced them .

b. What are the four benefits of reproducing asexually?

i. simple

ii. efficient

iii. effective

iv. produce a large number of offspring

c. Who can reproduce asexually? Prokaryotes (like bacteria)

6. Define sexual reproduction – offspring are produced by the fusion of two sex cells – one from each of two parents - These fuse into a single cell before the offspring can grow.

a. What is the benefit of sexual reproduction? The offspring produced inherit some genetic information from both parents.

b. Who can reproduce sexually? Most animals and plants, and many single-celled organisms, reproduce sexually.

7. Define genome – A cell’s endowment of DNA (its genetic information) is called its genome.

8. DNA molecules in a cell are packaged into ___________chromosomes___________.

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[Growth and reproduction] Introduction to Biology

Chromosomes

9. What is the purpose of chromosomes? The genetic information that is passed on from one generation of cells to the next is carried by chromosomes.

a. Every cell must _________copy its genetic information _________ before cell division.

b. Each new daughter cell gets ____its own copy of that genetic information ___.

c. Cells of every organism have ________a specific number of chromosomes_________.

10.Prokaryotic cells lack _________ nuclei ________.

a. Where is their DNA? In the cytoplasm

b. What form does their chromosome take? a single, circular DNA molecule, or chromosome, that contains most of the cell’s genetic

c. Draw a picture of a prokaryotic cell with chromosome below:

11. In eukaryotic cells, chromosomes are located in the ______nucleus_______ and are made of

_____chromatin________.

12.What is chromatin made of? Chromatin is composed of DNA and histone proteins.

13.What are nucleosomes? DNA coils around histone proteins to form nucleosomes.

14.What are chromosomes made of? The nucleosomes interact with one another to form coils and supercoils that make up chromosomes.

15.What must happen to prepare for cell division? DNA is replicated and the chromosomes condense

a. Each duplicated chromosome forms _______sister chromatids________.

b. What is the centromere? the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached

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[Growth and reproduction] Introduction to Biology

Phases of the Cell Cycle

16.The cell cycle consists of:

a. The Mitotic (M) Phase – (mitosis and cytokinesis)

b. Interphase – (cell growth and copying of chromosomes in preparation for cell division)

List the three parts of interphase:i. G1 phase (“first gap”)

ii. S phase (“synthesis”)

iii. G2 phase (“second gap”)

17.Label this diagram:

18.What happens in the G1 phase? cells increase in size and synthesize new proteins and

organelles19.What happens in the S phase? new DNA is synthesized when the chromosomes are

replicated20.What happens in the G2 phase? many of the organelles and molecules required for cell

division are produced

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[Growth and reproduction] Introduction to Biology

21.Describe the two phases of cell division in eukaryotes:

a. Mitosis – the division of the cell nucleus

b. Cytokinesis – the division of the cytoplasm

22.Define each of these important structures in mitosis:

a. Chromatid – each strand of a duplicated chromosome

b. Centromere – the area where each pair of chromatids is joined

c. Centrioles – tiny structures located in the cytoplasm of animal cells that help organize the spindle

d. Spindle – long proteins (part of the cytoskeleton) that the centrioles produce-Helps move the chromosomes into place.

23.Fill in this table for the different stages of mitosis:

Stage of Mitosis What Happens? What Does it Look Like?

InterphaseG1S

G2

Prophase

• the first phase of mitosis, the duplicated chromosome condenses and becomes visible. The centrioles move to opposite sides of nucleus and help organize the spindle. The spindle forms and DNA strands attach at a point called their centromere. The nucleolus disappears and nuclear envelope breaks down.

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[Growth and reproduction] Introduction to Biology

Metaphase

The second phase of mitosis, the centromeres of the duplicated chromosomes line up across the center of the cell. The spindle fibers connect the centromere of each chromosome to the two poles of the spindle.

Anaphase

The third phase of mitosis, the centromeres are pulled apart and the chromatids separate to become individual chromosomes. The chromosomes separate into two groups near the poles of the spindle.

Telophase

The fourth and final phase of mitosis, the chromosomes spread out into a tangle of chromatin. A nuclear envelope re-forms around each cluster of chromosomes. The spindle breaks apart, and a nucleolus becomes visible in each daughter nucleus.

24.What is cytokinesis? the division of the cytoplasm

25.Describe how cytokinesis occurs in animal cells: cytoplasm pinches in the middle until two cells form.

26.Why does the process have to be different in plant cells? In plants, the cell membrane is not flexible enough to draw inward because of the rigid cell wall

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[Growth and reproduction] Introduction to Biology

27.What forms instead in plant cells? a cell plate forms between the divided nuclei that develops into cell membranes

Binary Fission

28.Prokaryotes reproduce by a type of cell division called ________binary fission________.

29.What happens during binary fission? the chromosome replicates (beginning at the origin of replication), and the two daughter chromosomes actively move apart

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[Growth and reproduction] Introduction to Biology

30.The events of the cell cycle are controlled by a __distinct cell cycle control system, which is

similar to a clock__.

31.The control system has specific _____ checkpoints ______ where the cell cycle

______stops______ until a ________go-ahead signal______ is received.

32.Name the three cell cycle checkpoints:a. G1

b. G2

c. M

33.Which checkpoint is the most important? G1

a. What happens if the cell receives a go-ahead signal at this checkpoint? It will usually complete the S, G2, and M phases and divide

b. What happens if the cell does not receive a go-ahead signal? It will exit the cycle, switching into a non-dividing state called the G0 phase

34.Describe the two examples of cell growth control:

a. Density-dependent inhibition:

b. Anchorage dependence

35.What goes wrong with cancer cells? Cancer cells do not exhibit anchorage dependence or density-dependent inhibition.

36.What are tumors? Masses of abnormal cells within otherwise normal tissue.

a. What makes a tumor benign? crowded cells start dividing

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[Growth and reproduction] Introduction to Biology

b. What makes a tumor malignant? Malignant tumors invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form secondary tumors

DNA Replication37. When and where does DNA replication take place?

38. What are the three parts of a nucleotide?

39. What are the two purines?

40.What are the three pyrimidines?

41. How do nucleotides pair in DNA?

42. What do we call the model explaining how DNA replicates?

43. DNA serves only as a ________________________.

44. DNA polymerase enzymes bond the nucleotides together to form the

________________________________________.

45.Two new molecules of DNA are formed, each with

__________________________________________________________________.

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[Growth and reproduction] Introduction to Biology

46.DNA replication is _____________________________________. One strand is

____________________________ and the complimentary strand is

______________________.

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