SBI3U genetics unit part 1 review

DNA, chromosomes, cell cycle, mitosis, meiosis, mistakes in meiosis, gametogenesis

chromosomes

DNA

• aka deoxyribonucleic acid

• made up of nucleotides

DNA is classified as a protein

yes

centromere

it links a pair of sister chromatids together during cell division

nucleotide

chromatin

• made up of dna & histone proteins

• found during interphase of the cell cycle

What is the complementary base pairing rule

• Adenine (A) bonds with Thymine (T)

• Cytosine (C) bonds with Guanine (G)

what is hydrogen bonding

a type of chemical bond that weakly attaches a molecule to another molecule

how many H-bonds are between A & T

2 hydrogen bonds

how many h-bonds are between C & G

3 hydrogen bonds

meaning of anti-parallel

what is a gene

a piece of heredity material that is passed on from parent to offspring

what is an allele

a version of a gene at a particular position on a chromosome

what is heredity

the process of passing traits from parents to offspring

what is homologous chromosomes

a pair of chromosomes w/ the same type of genes

haploid cells (n)

• a cell w/ a single set of chromosomes

• humans sex cells have 23 chromosomes

diploid cells (2n)

• a cell that has 2 complete sets of chromosomes

• that # for humans is 46 chromosomes

somatic cells

• any cell that is not a sex cell

• are also diploid cells

gametes (sex cells)

• the reproductive cells of any animal or plant

• humans only have 23 chromosomes in their sex cells

• are also haploid cells

intramolecular bonds

forces that hold atoms together within a molecule

intermolecular bonds

forces that exist between molecules

stages of mitosis

1. Interphase (G1,S, G2)

2. Prophase

3. Metaphase

4. Anaphase

5. Telophase

purpose of mitosis

is cell divison ; for a mother cell to produce 2 daughter cells in the end

total # of chromosome for a human cell at the prophase stage of mitosis

46 chromosomes

the "n" description of the cell at interphase

2n

total # of chromosomes for a human cell at the prophase stage of mitosis

46 chromosomes

the "n" description of the cell at prophase

2×2n

total # of chromosome for a human cell at the end of the telophase stage of mitosis

46 chromosomes

the "n" description of the cell at the end of telophase

2n

where does mitosis occur

in somatic cells

G1 phase of Interphase

• cell does most of its growing; making it take in more nutrients

• DNA is spread throughout the nucleus as chromatin

• cell increases in size

• cell has 2n diffuse chromosomes (diploid)

S Phase (synthesis phase) of Interphase

• cell continues to grow

• the diffuse chromosome duplicates, producing a 2x2n # of diffuse chromosomes

G2 phase of Interphase

• cell has 2x2 n chromosomes within the nucleus

prophase

• nuclear membrane dissolves

• chromatin condenses into chromosome, each w/ 2 sister chromatinds attached by a centomere

• spindle fibers & centrioles assemble

• centrioles move to the poles of the cell

• 2x2n

what is meiosis

a special cell division that involves the production of reproductive cells

purpose of meiosis

to produce sex cells (sperms & eggs) that have half the genetic information of somatic cells

stages of meiosis

In meiosis I

• Prophase I

• Metaphase I

• Anaphase I

• Telophase I

In meiosis II

• Prophase II

• Metaphase II

• Anaphase II

• Telophase II

where does meiosis occur

in sex cells

synapsis

when 2 duplicated homologous chromosomes line up side by side

Chiasmata

the points of overlap where crossing over occurs

independent assortment

non-disjunction mistakes

when homologous chromosome fail to separate properly during cell division

mistakes during crossing over

• duplication

• deletion

• inversion

• translocation

duplication

when one chromosome ends up with two copies of a gene

deletion

the other chromosome would have no copies of that gene

inversion

the gene order on a chromosome switches

translocation

a gene from one chromosome ends up on a non-homologous chromosome

aneuploidy

the presence of an abnormal # of chromosomes in a cell

polyploidy

cells that have more than 2 sets of homologous chromosomes

would a human w/ polypIoidy survive

no

gametogenesis

the process where diploid gametes undergo meiosis to produce haploid gametes

polar body

a useless cell formed during oogenesis; it has chromosomes, but not much else

do all ovulated oocytes finish meiosis

oocytes only finish meiosis if they become fertilized

name of each cell that enters the body during spermatogenesis

spermatocyte

name of the cells that enter the body during oogenesis

oocyte

who determines the gender of a zygote

the father