Biology Flashcards: Ch 2 - Meiosis, Gametes & Fertilization

What is a prokaryote

a unicellular organisms with a relatively simple structure

What is a eukaryote

has a compartmentalized cell structure with components bound by intracellular membranes. Eukaryotes may be either unicellular or multicellular

What two organisms make up prokaryotes

bacteria and archaea

What are the three major groups of organisms

bacteria, archaea, and eukaryotes

What is the major difference between prokaryotic and eukaryotic cells

a eukaryotic cell has a nuclear membrane, which surrounds the genetic material to form a nucleus and separates the DNA from the other cellular content. In prokaryotic cells, the genetic material is in close contact with other components of the cell

What is another difference between prokaryotes and eukaryotes based on DNA

in eukaryotes, DNA associated closely with histones to from tightly packed chromosomes. this complex of DNA and histone proteins, called chromatin, is the stuff of eukaryotic chromosomes. Archaea have some histone proteins, but bacteria do not have histones

What do histone proteins do

help regulate the accessibility of DNA to enzymes and other proteins that copy and read the DNA, and they also enable the DNA to fit into the nucleus of a eukaryotic cell

What is another difference between prokaryotes and eukaryotes based on genes

the genes of prokaryotic cells are generally located on a single circular molecule of double-stranded DNA- the chromosome of a prokaryotic cell. In eukaryotic cells, genes are located of multiple, usually linear DNA molecules (multiple chromosome). Eukaryotic cells therefore require mechanisms to ensure that a copy of each chromosome is faithfully transmitted to each new cell

What are plasmids

important bacterial and archaeal genes frequently found on other DNA molecules

What are viruses

neither prokaryotic nor eukaryotic because they do not possess the structure of a cell. Viruses are actually simple structures composed of an outer protein coat surrounding nucleic acid. Viruses can only reproduce within host cells

What 3 events must take place for any cell to reproduce

1. its genetic information must be copied

2. the copies must be separated from each other

3. the cell must divide

When a prokaryotic cell reproduced, its circular chromosome replicates, and the cell divides in a process called _________

binary fission

where does replication begin

at a specific place of the circular chromosome called the origin of replication

proteins called ______________________ complexes encircle the DNA and help keep the two newly synthesized chromosomes from getting tangled as they are replicated

structural maintenance of chromosomes (SMC)

In most eukaryotic cells, there are two sets of chromosomes. The presence of two sets is a consequence of sexual reproduction: one set is inherited from the male parent and the other from the female parent. Each chromosome in one set has a corresponding chromosome in the other set; together, the two chromosomes constitute a ________

homologous pair

Cells that carry two sets of genetic information are ______

diploid

The reproductive cells of eukaryotes (such as eggs, sperm, and spores), and even the nonreproductive cells of some eukaryotic organisms, contain a single set of chromosomes and are __________

haploid

The cells of some other eukaryotes contain more than two sets of genetic information and are therefore called ______

polyploid

A functional chromosome has three essential elements, what are they

a centromere, a pair of telomeres, and origins of replication

the ___________ appears as a constricted region on the chromosome. it served as the attachment point for spindle microtubules.

centromere

What are spindle microtubules

the filaments responsible for moving chromosomes in cell division

Before cell division, a multiprotein complex called the _______ assembles on the centromere; later, spindle microtubules attach to the ______ (same answer)

kinetochore

What are the names/locations based on the four types of centromeres

- metacentric: right in the middle

- submetacentric: slightly towards one side

- acrocentric: really towards one side

- telocentric: at the very tip of one side

___________ are the specific DNA sequences and associated proteins located at the tips of whole linear chromosomes

telomeres

______________ are the sites where DNA synthesis begins; unlike centromeres and telomeres, they are not easily observed by microscopy

origins of replication

In preparation for cell division, each chromosome replicates, making a copy of itself. These two initially identical copies, called __________ are held together are the centromere

sister chromatids

The _________ is the series of stages through which a cell passes from one division to the next

cell cycle

List the phases of the cell cycle starting at cytokinesis

Cytokinesis, G1, possibly G0, G1/S checkpoint, S, G2, G2/M checkpoint, mitosis, spindle-assembly checkpoint, back to cytokinesis

What phases are part of interphase (cell growth) and what phases are part of M phase (nuclear and cell Division

-Interphase: Cytokinesis - G2/M checkpoint

-M phase: G2/M checkpoint - cytokinesis

What happens in G1

the cell grows

What happens in G0

cell may enter this phase, it is a non-dividing phase

What happens at the G1/S checkpoint

after the checkpoint, the cell is committed to dividing

What happens during S

DNA duplicates

What happens during G2

the cell prepares for mitosis

What happens at the G2/M checkpoint

after the checkpoint, the cell can divide

What phase happens after G2/M

mitosis and cytokinesis

what is the name of the phase that mitosis and cytokinesis are in

M phase, nuclear and cell division

Progression through the cell cycle is regulated at key transition points called ______, which allow or prohibit the cell's progression to the next stage

checkpoints

What is interphase

the period between cell divisions in which the cell grows, develops, and functions

What is the M (mitotic) phase,

the period of active cell division

What does the M phase include

mitosis and cytokinesis

What are the five stages of mitosis

prophase, prometaphase, metaphase, anaphase, telophase

What happens in prophase

chromosomes condense. each chromosome possesses two chromatids. the mitotic spindle forms

In prophase, a group of proteins called ________ bind to the DNA within chromosomes and bring about condensation

condensins

what happens in prometaphase

the nuclear membrane disintegrates. spindle microtubules attach to chromatids

What happens in metaphase

chromosomes line up on the metaphase plate

What happens in anaphase

sister chromatids separate and move toward opposite poles

What happens in telophase

chromosomes arrive at spindle poles. the nuclear membrane re-forms, and the chromosomes relax

What is the difference between a centromere and a centrosome

centromeres are in the middle of chromosomes, centrosomes are the things on the sides of the cells that the spindle fibers come out of

What are the two processes that make up meiosis

meiosis and fertilization

what is meiosis

leads to gametes in which the number of chromosomes is reduced by half

what is fertilization

two haploid gametes fuse and restore the number of chromosomes to its original diploid value

Meiosis consists of two distinct processes, what are they

meiosis I and meiosis II, each of which includes a cell division

What is synapsis

happens during meiosis I interphase, a very close pairing association

each homologous pair of synapses chromosomes, called a _____ or _____, consists of four chromatids

bivalent, tetrad

__________, in which homologous chromosomes exchange genetic information, takes place in prophase I

crossing over

each location where two chromosomes cross is called a ______

chiasma

The period between meiosis I and meiosis II is ______, in which the nuclear membrane re-forms around the chromosomes clustered at each pole, the spindle breaks down, and the chromosomes relax

interkinesis

Cells produced by meiosis are _____

haploid

After crossing over has taken place, what changed about the sister chromatids

they are no longer identical

Crossing over is the basis for intrachromosomal __________, the creation of new combinations of alleles on a chromatid

recombination

In general, the number of possible combinations is ______, where n equals the number of homologous pairs

2^n

Crossing over shuffles alleles on the ______ chromosome into new combinations, whereas the random distribution of maternal and paternal chromosomes shuffles alleles on _______ chromosomes into new combinations

same, different

______, a protein that holds chromatids together, is key to the behavior of chromosomes in mitosis and meiosis. It has a ring-like structure that encircles and holds together the sister chromatids

Cohesin

Cohesin at the centromere is protected by a protein called _______

shugoshin

What is the process of shugoshin

because of the protective action of shugoshin, the centromeric cohesin remains intact and prevents the separation of the two sister chromatids during anaphase I. Shugoshin is subsequently degraded. at the end of metaphase II, the centromeric cohesin- no longer protected by shugoshin- breaks down, allowing the sister chromatids to separate in anaphase II.

The production of gametes in a male animal, a process called ______, takes place in the testes

spermatogenesis

there, diploid primordial germ cells divide mitotically to produce diploid cells called ________

spermatogonia

the production of gametes in a female animal, a process called _______, begins much as spermatogenesis does

oogenesis

within the ovaries, diploid primordial germ cells divide mitotically to produce _____

oogonia

the smaller cell is called the _____, the larger cell is the _____, the mature female ovum

second polar body, ovum

Most multicellular plants have a complex life cycle that includes two distinct structures (generations): a multicellular diploid _____ and a multicellular haploid______

sporophyte, gametophyte

These two generations alternate, the sporophyte produces haploid spores through meiosis, and the gametophyte produces haploid gametes through mitosis. this type of life cycle is sometimes called _______________

alternation of generations

in this cycle, the immediate products of meiosis are called _____ not gametes

spores

the male part of the flower, the stamen, contains diploid reproductive cells called __________, each of which undergoes meiosis to produce four haploid _______

microsporocytes, microspores

the female part of the flower, the ovary, contains diploid cells called ______, each of which undergoes meiosis to produce four haploid ______, only one of which survives

megasporocytes, megaspores