Unit 5 - Heredity

Question 1

common ancestry

Answer 1

• DNA and RNA carry genetic info
• genetic code is shared by all living systems
• Gregor Mendel studied inheritance and created two laws that can be applied to the study of genetics

Question 2

genetics

Answer 2

study of heredity and hereditary variation

Question 3

heredity

Answer 3

transmission of traits from one generation to the next

Question 4

traits are passes from parent to offspring through…

Answer 4

genes

Question 5

asexual reproduction

Answer 5

• single individual
• no gamete fusion
• clones
• mutations are only source of variation
• can produce asexually through mitosis
• advantage: quick & easy

Question 6

sexual reproduction

Answer 6

• 2 parents
• offspring are unique combinations of genes
• genetically varied from family
• the less related you are to your partner, the smaller the chance for genetic disorder
• disadvantage: takes longer

Question 7

homologous chromosomes

Answer 7

pair of chromosomes that carry same genetic information (inherited one from mom/dad)

Question 8

karyotypes

Answer 8

display of chromosome pairs ordered by size and length

Question 9

somatic cells

Answer 9

• body cells
• diploid (2n)
• 2 complete sets of each chromosome

Question 10

gametic cells

Answer 10

• sex cells
• haploid (n)
• one set of each chromosome

Question 11

eukaryotes

Answer 11

have DNA that is packaged in chromosomes

Question 12

autosomes

Answer 12

chromosomes that do not determine sex

Question 13

sex chromosomes

Answer 13

X and Y
23rd chromosome pair

Question 14

eggs

Answer 14

X

Question 15

sperm

Answer 15

X or Y

Question 16

life cycle

Answer 16

sequence of stages in reproductive history of an organism form conception to its own conception

Question 17

fertilization and meiosis…

Answer 17

alternate in sexual life cycles

Question 18

fertilization

Answer 18

sperm cell (haploid) fuses with an egg (haploid) to form a zygote (diploid)

Question 19

all sexually reproducing organisms have

Answer 19

both a diploid and a haploid number

Question 20

meiosis

Answer 20

process that creates haploid gamete cells in sexually reproducing diploid organisms

Question 21

meiosis results in daughter cells with…

Answer 21

half the number of chromosomes as the parent cell

Question 22

mitosis

Answer 22

• occurs in somatic cells
• 1 division
• results in 2 diploid daughter cells
• daughter cells are genetically identical

Question 23

meiosis

Answer 23

• forms gametes (sperm/egg)
• 2 divisions
• results in 4 haploid daughter cells
• each daughter cell is genetically unique

Question 24

three key events of meiosis

Answer 24

prophase I, metaphase I, anaphase I

Question 25

prophase I

Answer 25

- synapsis and crossing over - crossing over (recombination) occurs at the chiasmata and DNA is exchanged between the homologous pairs - every chromatid that is produced has a unique combination of DNA

Question 26

metaphase I

Answer 26

independent orientation: tetrads (homologous pairs) line up at metaphase plate

Question 27

anaphase I

Answer 27

homologous pairs separate

Question 28

interphase

Answer 28

cell goes through G1, S, G2

Question 29

synapsis

Answer 29

homologous chromosomes pair up and physically connect to each other forming a tetrad

Question 30

anaphase I

Answer 30

- pairs of homologous chromosomes separate - sister chromatids are still attached

Question 31

telophase I and cytokinesis

Answer 31

- nuclei and cytoplasm divide - there is now a haploid set of chromosomes in each daughter cell

Question 32

prophase II

Answer 32

- no crossing over - spindle forms

Question 33

metaphase II

Answer 33

- chromosomes line up at the metaphase plate - because of crossing over in meiosis I, the chromatids are unique

Question 34

anaphase II

Answer 34

sister chromatids separate and move towards opposite poles

Question 35

telophase II and cytokinesis

Answer 35

- 4 haploid cells - nuclei reappear - each daughter cell is genetically unique

Question 36

early meiosis I

Answer 36

parent cell: 2n = 4

Question 37

end of telophase II and cytokinesis

Answer 37

each daughter cell: n = 2

Question 38

how does meiosis lead to genetic variation

Answer 38

- crossing over - independent assortment of chromosomes

Question 39

crossing over