Genes are the units of __________ which make up our segments of _____

hereditary, DNA

Sequences of _______ make up genetic information

nucleotides

In plants and animals, gametes (egg or sperm) transmit genes from ______ to ______

parent, offspring

DNA is subdivided into ________ in _______

chromosomes, nucleus

Living organisms are distinguished by their ability to reproduce their______

own kind

cats produce

cats

maple trees produce

maple trees

Heredity is the _____ of traits from one _____ to the next

transmission, generation

generation=

inheritance

Variation: shows that _____ differ somewhat in appearance from ______ and _____

offspring, parents, siblings

Variation: shows that offspring differ somewhat in appearance from parents and siblings even though they inherit ______

similar traits

Genetics: the scientific study of ___ and ___

heredity, hereditary variation

Chromosome contains a single long _______ w/ ______

DNA molecule coiled, various proteins

One chromosome has ___ of genes each of which has a specific sequence of _____

thousands, nucleotides

Each gene in an organism’s DNA has a specific ____ on a certain chromosome

locus

Locus: area on the ___ where a specific gene is located

chromosome

We inherit one set of chromosomes from our ___and one set from our ___

mother, father

In humans: __ chromosomes in somatic cells

46

In asexual reproduction, one __ produces ______ offspring by _____

parent, genetically identical, mitosis

Clone: group of ______ individuals produced by _____ parents

genetically identical, asexually reproducing

In sexual reproduction, two __ give rise to offspring that have _____ of genes inherited from the __parents

parents, unique combinations, 2

siblings can be __ but not __

similar, identical

Siblings vary ______ from each other and parents

genetically

____ and ___is alternate in sexual life cycles

fertilization, meiosis

A life cycle is the __________ of stages in the ____ of an organism (in this case humans)

generation-to-generation sequence, reproductive history

In humans each somatic cell (body cell) has __ chromosomes, made up of __sets

46, 2

_____ pairs of chromosomes

23

__ set of chromosomes comes from each parent

1

A karyotype is a ________ of the ___ in a __

ordered visual representation, chromosomes , cell

a karyotype represents _______ or _____

homologous chromosomes, homologs

Homologous chromosomes (aka: homologs) Are the_____ composing a ____

2 chromosomes, pair

Homologous chromosomes (aka: homologs) have the same ____ (length, centromere position, and staining pattern)

characteristics

Homologous chromosomes (aka: homologs) each pair of chromosomes carry ____, _____, the____ inherited characteristics

genes, controlling same

Homologous chromosomes (aka: homologs) may have different __ of those___

variations, characteristics

First 22 pairs of homologs are called ____

autosomes

Sex chromosomes Are ___ from each other in their characteristics

distinct

Sex chromosomes Are represented as ___ and ___

X,Y

Sex chromosomes determine the ___ of the individual

sex

Number of chromosomes in a single set is represented by ___

n

A diploid cell has the ___ set of______ chromosomes

complete, all homologous

a human has 46 chromosomes express in diploid equation:

(2n = 46)

haploid cell is represent as

n

a diploid cell is represented as

2n

One set of 23 from____ and one set of 23 from _____

mom, dad

Somatic cells are

diploid cells

In a cell in which DNA synthesis has occurred all the chromosomes are _____ and thus each consists of ________

duplicated, two identical sister chromatids

Gametes, sperm and egg cells, are ___ cells containing only ___ set of chromosomes

haploid, 1

22 autosomes and 1 sex chromosome =

23 chromosomes

Unfertilized eggs only contain an __ chromosome

X

a sperm cell can contain an __ or a ___ chromosome

X, Y

When fertilization occurs, a ____ cell is formed and the offspring gets one set of chromosomes from the ___ and one from the ____

diploid, father, mother

At sexual maturity, the ovaries and testes (gonads) produce ____ gametes by ____ in special cells called ____ cells

haploid, meiosis, germ

Meiosis: cell division that ___ the number of sets of chromosomes from ___ to __ in the gametes

reduces. 2, 1

During fertilization these gametes, sperm and ovum (egg), ___, forming a _____

fuse, diploid zygote

The zygote develops into an ____ by _____

adult organism, mitosis

The three main types of sexual life cycles differ in the timing of ___ and ____ according to the spp.

meiosis, fertilization

The three main types of sexual life cycles share one thing in common:

genetic variation

In animals ____ occurs during gamete formation

meiosis

In animals gametes are the only ____ cells

haploid

Plants and some algae exhibit an :

alternation of generations

Plants and some algae's life cycle includes both ( ) and ( ) ( ) stages

diploid, haploid, multicellular

In Plants and some algae the diploid stage is called the ( ) and haploid called spore and gametophyte

sporophyte

In Plants and some algae the haploid stage is called the ( ) and ( )

spore,gametophyte

In most fungi and some protists meiosis produces ___ cells that give rise to a haploid _____ adult organism

haploid, multicellular

In most fungi and some protists the haploid adult carries out _____, producing cells that will become _____

mitosis, gametes

Depending on the type of life cycle, either ____ or ____ cells can divide by _____

haploid, diploid, mitosis

However, only ____ can undergo _____

diploid, meisosis

In all three life cycles the ____ and _____ of chromosomes contribute to ______ in offspring

halving, doubling, genetic variation

Meiosis reduces the number of chromosome sets from _____ to ____

diploid, haploid

Even though meiosis reduced the number of chromosomes from diploid to haploid they still have ____ before meiosis

interphase

Meiosis takes place in how many numbers of sets of cell division

2

What are the names of the 2 sets of cell divisions in meiosis

meiosis 1 and meiosis 2

Meiosis results in ____ daughter cells with ___ the number of chromosomes than the ____ cell

4, half, parent

Meiosis 1 reduces the number of chromosomes from ____ to _____

diploid, haploid

Meiosis 1 contains what stages (4)

prophase 1

metaphase 1

anaphase 1

telophase 1

Meiosis 2 produces ___, ___ daughter cells

4, haploid

Meiosis 2 contains what stages (4)

prophase 2

metaphase2

anaphase 2

telophase 2

In early prophase 1 each chromosome pairs with its __

homolog

In early prophase 1 what occurs

crossing over

What are x-shaped regions called

chiasmata

chiasmata are sites of

crossovers

In metaphase 1 pairs of homologs line up at the ______ with ___ chromosome facing each pole

metaphase plate, 1

Microtubules from one pole are attached to the ____ of one chromosome of each pair and same goes for the other pole.

kinetochore

In anaphase 1 pairs of homologous chromosomes _____

separate

In anaphase 1, 1 chromosome of each pair moves toward opposite poles guided by the ______

spindle apparatus

In anaphase 1 sister chromatids remain ____ at the ______ and move as 1 unit towards the ____

attached, centromere, pole

In the beginning of telophase 1 each half of the cell has a ___ set of chromosomes

haploid

Each chromosome consists of _____

2 sister chromatids

Cytokinesis usually occurs _____ forming _____

simultaneously, 2 haploid daughter cells

In animal cells a __________ forms

cleavage furrow

In plant cells a ______ forms

cell plate

No chromosomal replication occurs between the end of ____ and the beginning of _____ because the chromosomes are already replicated

meiosis 1 , meiosis 2

In prophase 2 , a _____ forms

spindle apparatus

In late prophase 2, chromosomes move towards the _____

metaphase plate

In metaphase 2 the sister chromatids are arranged at the ____

metaphase plate

Because of crossing over in meiosis 1 the 2 sister chromatids of each chromosome are no longer _____

genetically identical

In metaphase 2 the kinetochore of sister chromatids attach to _____ extending from _____ poles

microtubules, opposite

In anaphase 2, the sister chromatids

separate

In anaphase 2 the sister chromatids of each chromosome now move as 2 _____ chromosomes toward ______ poles

newly individual, opposite

In telophase 2 , the chromosomes arrive at _____ poles

opposite

In telophase 2 _____ forms

nuclei

In telophase 2 the chromosomes begin _____

decondensing

Cytokinesis separates the

cytoplasm

at the end of meiosis, there are __ daughter cells, each with a haploid set of ______ chromosomes

4, unreplicated

Each daughter cell is _______ from the others and from the parent cell

genetically different

replicated homologs pair up and become connected by a zipper-like protein structure known as the

synaptonemal complex

replicated homologs pair up and become connected by a zipper-like protein structure (synaptonemal complex) this process is known as

synapsis

Meiosis and mitosis can be distinguished from mitosis by __ events in Meiosis 1

3

The process of synapsis dissembles expect for one area called the

chiasma

The process of synapsis dissembles expect for one area (the chiasmata) where ____ occurs

crossing over

crossing over occurs: genetic rearrangement between _____

nonsister chromatids

each tetrad contains a

chiasma

a tetrad is ____ chromatids of ______ pair

4, homologous

at metaphase 1 of meiosis paired homologous chromosomes (tetrads) are positioned on the _____

metaphase plates

at metaphase 1 of meiosis paired homologous chromosomes (tetrads) are positioned on the metaphase plates rather than _________ chromosomes

individual replicated

at anaphase 1 of meiosis homologous pairs move toward _____ poles of the cell

opposite

At anaphase 1 of meiosis cohesins are ___ along chromosome arms to separate _____

cleaved, homologs

In anaphase 2 of meiosis the sister chromatids____

separate

In anaphase 2 of meiosis cohesins are ___ at the ___ to separate ____

cleaved, centromere, sister chromatids

Genetic variation contributes to

evolution

Reshuffling of genetic material in meiosis produces

genetic variation

Reshuffling of genetic material in meiosis produces genetic variation because it creates different ______ of genes

versions

Originally due to mutations: change in the DNA sequence to cause different versions of genes are called

alleles

Is eye color a gene or allele

gene

Is blue vs. brown eye color a gene or allele?

allele

In species that produce sexually the behavior of chromosomes during ____ and ____ are responsible for most of the variation that arises each generation

meiosis , fertilization

How many mechanisms are there that contribute to genetic variation

3

What are the 3 mechanisms that contribute to genetic variation

Independent assortment of chromosomes

Crossing over

Random fertilization

homologous pairs of chromosomes orient randomly at _____ of _____

metaphase 1, meiosis 1

Within homologous pairs of chromosomes each pair may orient with either the ___ or ____ homolog independently of other pairs

maternal, paternal

In humans, there are more than ____ million possible combinations of chromosomes

8

Crossing over produces _____ chromosomes that carry ____ derived from 2 _____

recombinant, genes, different parents

In humans, average of ___-____ crossover events occurs per chromosome

1-3

The fusion of gametes will produce a ____ with any of about ____ trillion diploid combinations

zygote, 70

With the fusion of gametes you don't know which ___ will fertilize which ___

sperm, ovum

Mutations are the _____ source of _______

original, genetic variation

Sexual reproduction produces new ___ of ____ genes adding more ____

combinations, variant, genetic diversity