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Biology 160 > BIO 160 Chapter 8 > Flashcards

BIO 160 Chapter 8 Flashcards

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1
Q

cell division

A

the two daughter cells that result are genetically identical to each other

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2
Q

asexual reproduction

A

does not involve the fertilization of an egg by a sperm

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3
Q

sexual reproduction

A

requires fertilization of an egg by a sperm

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4
Q

gametes

A

egg and sperm

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5
Q

meiosis

A

cell division which occurs in reproductive organs

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6
Q

histones

A

small proteins used to package DNA

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7
Q

nucleosome

A

are proteins used to package DNA in

eukaryotes

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8
Q

centromere

A

narrow “waist” that joins sister chromatids,holds the sister chromatids
together

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9
Q

cell cycle

A 
A cell cycle is the ordered sequence of events that 
lead to cell division
• Interphase
• Mitosis
– Prophase
– Metaphase
– Anaphase
– Telophase
– Cytokinesis
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10
Q

interphase

A

a time when a cell performs is normal functions within an organism

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11
Q

mitotic phase

A

part of the cell cycle when the cell is actually dividing

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12
Q

cytokinesis

A

the cytoplasm is divided into two

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13
Q

eukaryotic cells

A

• most genes are located on chromosomes in the cell
nucleus and
• a few genes are found in DNA in mitochondria and
chloroplasts.
• Nucleus contains lots of DNA and genes
• Number of chromosomes in a eukaryotic cell depends
species.

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14
Q

chromatin

A

fibers composed of roughly equal amounts
of DNA and protein molecules and
– not visible in a cell until cell division occurs

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15
Q

when is DNA replicated?

A

DNA is replicated during s-phase, resulting in

sister chromatids containing identical genes

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16
Q

what happens during interphase?

A

During interphase, a cell:
• Functions normally
• Duplicates everything in cytoplasm
• Grows in size

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17
Q

what happens during mitotic phase?

A

• Mitosis: when nucleus and its contents divide evenly
into 2 daughter nuclei
• Cytokinesis: when cytoplasm is divided into two

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18
Q

mitosis

A

– Results in two identical daughter cells
– Functions:
• replaces damaged or lost cells (tissue repair)
• permits growth (growth)
• allows for reproduction (asexual)

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19
Q

interphase

A

each chromosome replicates in late interphase, resulting in two sister chromatids connected at the centromere, chromosomes are loosely gathered at the nucleus

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20
Q

prophase

A

replicated chromosomes begin to coil up
nuclear membrane begins to disassemble
protein fibers of mitotic spindle begin to form

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21
Q

prometaphase

A

chromosomes condense to shorten them, making it easier to separate
spindle fibers attach to chromosomes on both sides at the centromere region

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22
Q

metaphase

A

spindle fibers from opposite sides begin to pull on chromosomes
chromosomes are aligned along middle of cell

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23
Q

anaphase

A

spindle fibers shorten and pull sister chromatids to opposite ends of the cell

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24
Q

telophase

A

an identical set of chromosomes reaches each pole
spindle fibers disassemble
nuclear membrane forms around each set of chromosomes, forming the daughter cell nuclei

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25
cytokinesis
• During cytokinesis, the cell membrane pinches in to completely surround each new daughter cell. • The cell cycle starts over with two newly formed identical daughter cells in interphase. Each daughter cell has the same number of chromosomes as the parent cell
26
how does cytokinesis differ in plants and animals?
– In animal cells • known as cleavage • begins with the appearance of a cleavage furrow, an indentation at the equator of the cell. – In plant cells • cytokinesis begins when vesicles containing cell wall material collect at the middle of the cell and then fuse – forms membranous disk called the cell plate.
27
What happens when cell cycle goes | out of control?
Specialized cell cycle factors normally regulate cell proliferation by sending “stop” or “go”signals. • Tumor suppressor genes lose ability to regulate cell division • Oncogenes gain ability to always be active
28
Tumor suppressor genes
Tumor suppressor genes lose ability to regulate cell BRAKES | division
29
oncogenes
Oncogenes gain ability to always be active GAS
30
What is cancer?
– Uncontrolled cell proliferation – Cancer cells can form tumors, abnormally growing masses of body cells. – If the abnormal cells remain at the original site, the lump is called a benign tumor
31
tumor
abnormally growing mass of body cells
32
metastasis
The spread of cancer cells beyond their original | site of origin is metastasis
33
malignant tumor
• spread to other parts of the body and • interrupt normal body functions. – Patients w malignant tumor have cancer
34
cancer treatment
– Resection: removal of tumor – Radiation therapy: damages DNA and disrupts cell division – Chemotherapy: uses drugs to disrupt cell division
35
resection
removal of tumor
36
radiation therapy
damages DNA and disrupts cell | division
37
chemotherapy
uses drugs to disrupt cell division
38
meiosis
– Results in four haploid gametes – Functions: • To increase genetic diversity (ie offspring have slightly different genetic makeup compared to parents) • Allows sexual reproduction • Keeps the chromosome number from doubling every generation.
39
somatic cell
– A human somatic cell • is a typical body cell • has 46 chromosomes
40
karyotype
A karyotype is an image that reveals an orderly | arrangement of chromosomes.
41
homologous chromosome
* are matching pairs of chromosomes | * can possess different versions of the same genes
42
sex chromosomes
X or Y
43
autosomes
matching chromosomes
44
life cycle
The life cycle of a multicellular organism is the sequence of stages leading from the adults of one generation to the adults of the next.
45
diploid organism
Humans are diploid organisms with • body cells containing two sets of chromosomes • Haploid gametes that have only one member of each homologous pair of chromosomes
46
diploid zygote
In humans, a haploid sperm fuses with a haploid egg | during fertilization to form a diploid zygote
47
meiosis process
– Haploid daughter cells are produced in diploid organisms. – Interphase is followed by two consecutive divisions, meiosis I and meiosis II. – Genetic diversity increases through DNA recombination (crossing over) and independent assortment
48
mitosis vs meiosis
– Chromosomes duplicate only once (in S-phase of Interphase) – The number of cell divisions varies: • Mitosis: one division and produces two diploid cells. • Meiosis: two divisions and produces four haploid cells. – All the events unique to meiosis occur during meiosis I.
49
origins of genetic variations
– Offspring of sexual reproduction are genetically different from their parents and one another. – Mechanisms • DNA recombination (Prophase I of Meiosis) • Independent assortment (Metaphase I of Meiosis) • Random fertilization
50
DNA recombination
– In crossing over, • nonsister chromatids of homologous chromosomes exchange corresponding segments • Genetic recombination, the production of gene combinations different from those carried by parental chromosomes, occurs
51
independent assortment
• Homologous chromosomes align at Metaphase I randomly • Homologous chromosome pairs align independently of other chromosomes • Total number of chromosome combinations that can appear in gametes due to independent assortment is 2 n , where n is the haploid number – For humans: 2 23 , there are 8,388,608 different chromosome combinations possible in a gamete
52
random fertilization
• Fertilization between egg and sperm is random • If each gamete is 1 in 8,388,608 different chromosome combinations, humans have >70 trillion (8,388,608x8,388,608) different chromosome combinations
53
nondisjunction
• Occurs when members of a chromosome pair fail to separate at anaphase • produces gametes with an incorrect number of chromosomes • Can occur during meiosis I or II
54
what happens when errors occur in meiosis?
If nondisjunction occurs, and a normal sperm fertilizes an egg with an extra chromosome, the result is a zygote with a total of 2n + 1 chromosomes. – If the organism survives, it will have • an abnormal karyotype and • probably a syndrome of disorders caused by the abnormal number of genes.
55
down syndrome
– Trisomy 21 – A condition where an individual has an extra chromosome 21 – Affects ~1 in 700 children – The incidence of Down syndrome in the offspring of normal parents increases markedly with the age of the mother.
56
roles of cell division in living organisms
cells must divide to replace damaged or ost cells, growth and reproduction
57
describe structure of a chromosome
helix. histones, nucleosome, centromere
58
explain how and when chromosomes are duplicated
before the cell divides and DNA molecule is copied and proteins attach as needed, each chromosome consists of two copies called sister chromatids.
59
describe key events of the cell cycle
interphase- doubles everything in cytoplasm, increases supply of proteins, increases number of organelles.. duplicates chromosomes mitotic phase- 2 daughter nuclei formed cytokinesis- cytoplasm splits
60
s phase
DNA replication
61
g phases
gap phases between s phase G1 G2
62
how are tumor cells different than healthy cells of the body?
tumor abnormally growing in body, healthy cells have gas or brakes...
63
benign vs malignant
benign stays at original site, malignant spreads to surrounding tissue
64
slash burn and poison
remove tumor, radiate "burn" cells, poison, drugs used to disrupt cell division
65
sex chromosomes vs autosomes
sex chomosomes, non matching pair, | autosome all match
66
somatic cells vs gametes
somatic cells have 46 chromosomes somatics go through mitosis, gametes go through meiosis
67
diploid vs haploid
diiploid - homologous chromosomes | haploid - a single chromosome set

Biology 160 (11 decks)

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