Chapter 12

Question 1

A distinguishing characteristic of living things from nonliving things

Answer 1

the ability of organisms to reproduce

Question 2

the continuity of life is based upon…

Answer 2

the reproduction of cell, or cell division

Question 3

Unicellular organisms

Answer 3

reproduce an entire organism by cell division

i.e. amoeba

Question 4

Multicellular organisms

Answer 4

depend on cell division for multiple processes including: development from a fertilized cell or egg, growth of cells to develop tissues, and repair and renew cells that die from normal wear and tear or accidents

Question 5

3 reasons for Mitosis to occur

Answer 5

1) Reproduction
2) Growth and development
3) Tissue renewal

Question 6

Cell division is

Answer 6

part of the cell cycle

Question 7

Cell cycle

Answer 7

the life of a cell from its origin in the division of a parent cell until its own division into two new cells

Question 8

Cell division requires

Answer 8

the distribution of identical genetic material – DNA - to 2 daughter cells

Question 9

Cells duplicate their genetic material

Answer 9

before they divide, ensuring that each daughter cell receives an exact copy of the genetic material, DNA

Question 10

Genome

Answer 10

(a cell’s endowment of DNA, its) genetic information

can range from a single DNA molecule (prokaryotes) to several DNA molecules (eukaryotes)

Question 11

DNA molecules in a cell are packaged into

Answer 11

chromosomes

Question 12

(Eukaryotic) Chromosomes

Answer 12

have a characteristic number in each nucleus depending on the species and consist of chromatin

Question 13

Chromatin

Answer 13

a complex of DNA and protein that condenses during cell division

Question 14

in animals, somatic cells…

Answer 14

have two sets of chromosomes

-i.e. human somatic cells have 46 chromosomes (2 sets of 23 from each parent)

Question 15

in animals, gametes

Answer 15

have one set of chromosomes

Question 16

In preparation for cell division, DNA…

Answer 16

is replicated and the chromosomes condense to make a small package

Question 17

Each duplicated chromosome has…

Answer 17

2 sister chromatids, which separate during cell division and contain identical DNA

Question 18

During Condensation (of cell division)

Answer 18

the chromatids are connected at a narrow area, called the centromere

Question 19

Centromere

Answer 19

narrow area at which the chromatids are connected

Question 20

Later in cell division,

Answer 20

the chromatids are pulled apart into the new nuclei at opposite ends of the parent cell to form individual chromosomes

Question 21

Eukaryotic cell division consists of

Answer 21

mitosis

Question 22

mitosis

Answer 22

the division of the nucleus (karyokinesis), cytokinesis, and maintenance of the chromosome number

Question 23

Karyokinesis

Answer 23

the division of the nucleus

Question 24

Cytokinesis

Answer 24

the division of the cytoplasm

Question 25

Meiosis

Answer 25

sex cells (gametes) have a reduction in chromosome number - yield 4 nonidentical daughter cells - each with half the chromosomes of the parent

Question 26

Cell cycle

Answer 26

consists of the mitotic (M) phase which alternates with the longer interphase

Question 27

mitotic phase is made up of

Answer 27

karyokinesis and cytokinesis

Question 28

Interphase

Answer 28

the cell grows and prepared for cell division divided into sub-phases: G1, S, and G2 G = growth phases S = DNA synthesis (replication)

Question 29

5 distinct phases or steps in mitosis

Answer 29

1) Prophase 2) Prometaphase 3) Metaphase 4) Anaphase 5) Telophase (and cytokinesis)

Question 30

Prophase

Answer 30

the chromosomes are tightly packed, chromatids are joined, and the mitotic spindle begins to form

Question 31

Prometaphase

Answer 31

the nuclear envelope fragments, the microtubules from the spindle interact with the chromosomes, and the chromatids contain a kinetochore

Question 32

Metaphase

Answer 32

sister chromatids are arranged at the metaphase plate

Question 33

Metaphase plate

Answer 33

an imaginary plane equidistant from the poles of the cell

Question 34

Anaphase

Answer 34

the centromeres divide separating the sister chromatids which are pulled toward the poles

Question 35

Telophase

Answer 35

daughter nuclei begin to form at the 2 poles and nuclear envelopes begin to arise

Question 36

Mitotic Spindle

Answer 36

an apparatus of spindle microtubules and asters that controls chromosome movement during mitosis and arises from the centrosomes soem spindle microtubules attach to the kinetochores of chromosome and move the chromosomes to the metaphase plate

Question 37

In animal calls, Cytokinesis

Answer 37

follows mitosis (karyokinesis) and occurs by a process known as cleavage, which first appears by forming a cleavage furrow in the cell surface near the metaphase plate Within the cytoplasm, is a contractile ring of actin microfilaments that facilitates and pinches the cell in two

Question 38

Prokaryotes (bacteria) reproduce by a types of cell division called...

Answer 38

binary fission | typically more rapid than in eukaryotes

Question 39

During binary fission,

Answer 39

the bacterial chromosome, which is circular DNA, replicates and the 2 daughter chromosomes actively move apart 1) Chromosome replication begins. Soon thereafter, one copy of the origin moves rapidly toward the other end of the cell 2) Replication continues. One copy of the origin is now at each end of the cell 3) Replication finishes. The plasma membrane grows inward, and new cell wall is deposited 4) 2 daughter cells result

Question 40

Regulation of Cell Cycle

Answer 40

the timing and rates of cell cycle division is crucial for normal growth and development of an organism and is carefully regulated by an exquisite molecular control system

Question 41

Frequency of cell division

Answer 41

varies among cell types and the molecules and enzymes present in the cytoplasm also regulate progress through the cell cycle

Question 42

The sequential events of the cell cycle are directed by a

Answer 42

distinct cell cycle control system | (similar to a clock) with cyclinally operating enzymes to coordinate the cell cycle

Question 43

The clock has

Answer 43

specific checkpoints where the cell cycle stops until a go-ahead signal is received

Question 44

The signals are transmitted by..

Answer 44

signal transduction pathways with three major checkpoints in the G1, G2, and M phases i.e. EGF (epidermal growth factor)

Question 45

G1 checkpoint

Answer 45

restriction point | the most important

Question 46

p53

Answer 46

is a tumor suppressor - protein - regulated gene - cell health indicator: detect mutations mutated p53 can cause cancer

Question 47

Internal and External signals

Answer 47

control the cell cycles checkpoints: 1) Growth factors: stimulate other cells to divide (i.e. EGF) 2) Density-dependent inhibition: over-crowded cells stop dividing 3) most animal cells exhibit Anchorage Dependence in which they must be attached to a substratum to divide (i.e. EGF)

Question 48

Cancer cells

Answer 48

do not respond normally to the body's control mechanisms and form tumors exhibit neither dentist-dependent inhibition nor anchorage dependence overgrowth leads to tumors and anchorage-independence results in Metastasis (spreading) can form clump of overlapping cells

Question 49

Malignant Tumor

Answer 49

invade surrounding tissues and can metastasize exporting cancer cells to other parts of the body where they may form secondary tumors