Chapter 6 Chromosomes and Cell Reproduction Why Its

Chapter 6 Section 1 Chromosomes Objectives • Identify four examples of cell division in

6 -1 Vocabulary • • Gamete Binary fission Gene Chromosome Chromatid Centromere homologous chromosome

Chapter 6 Section 1 Chromosomes Formation of New Cells by Cell Division reproduction •

• Before a cell can divide, the DNA must first be copied and

• Prokaryotes carryout a very simple type binary of cell division called _______

• The original cell divides by adding membrane a new cell _______ between

asexual • Binary fission is a form of _________ reproduction because…. single – It

Eukaryotic Cells • Before eukaryotic cells divide, their DNA is ______ and referred uncoiled

• Your DNA is normally uncoiled code it contains is because the _____

• Before a eukaryotic cell divides, the DNA is ______, and it _____

• Next, the nucleosomes actually end up coiling _____ on themselves to form

• This supercoil is tightly packed in a structure called a ________ chromosome

• Chromosomes have two ________ sides identical because they contain DNA that copied

• These sister chromatids separate at the ________ centromere during cell division to

Chapter 6 Section 1 Chromosomes Different species contain different numbers of chromosomes Ex: Humans

Asexual Reproduction – Eukaryotic cells exact copies of • Eukaryotic cells will make _____

• Asexual reproduction only occurs in body cells which are also called __________

46 chromosomes, • All of your somatic cells contain ____ diploid cells which means

Sexual Reproduction – Eukaryotic Cells One pair of your chromosomes are called your •

X • Your two sex chromosomes are referred to as _____ Y and _____

sex • Your _____ cells reproduce sexually because two cells are needed to make

• If human somatic cells (2 n) have 46 chromosomes…how many chromosomes do

` The zygote will then continue to grow and develop through mitosis ______ into

• Interesting Question… – If a zygote divides and grows through mitosis, how

` In order for sexual reproduction to occur, organisms must inherit homologous ______ chromosomes,

` Your 46 chromosomes are 2 sets or actually ____ pairs of homologous chromosomes

According to the diagram, how many chromosomes would the zygote of a human offspring

That would be bad! Having too many or too few chromosomes can result in

Sometimes an individual may inherit an incorrect number of chromosomes if the chromosomes fail

• Example: Down syndrome This condition is also trisomy called _______ 21 because

Chapter 6 Section 1 Chromosomes You can also identify sex in a karyotype Does

Chapter 6 Section 1 Chromosomes Your sex chromosomes are the only chromosomes that are

Chromosomal Mutations • Breakage of a chromosome can lead to four types of mutations

Deletion • Occurs when a gene from a chromosome breaks off or is ________

Review • How is a gene deletion different from a deletion in a frameshift

Duplication attaches • Occurs when a chromosome fragment ______ to its homologous chromosome 1

Inversion • Occurs when a chromosome fragment breaks off and order reattaches in the

Translocation • Occurs when a chromosome fragment breaks off and nonhomologous attaches to a

Objective 1 • Identify four examples of cell division in eukaryotes and one example

Objective 2 • Differentiate between a gene, a DNA molecule, a chromosome, and a

Objective 3 • Differentiate between homologous chromosomes, autosomes, and sex chromosomes. Homologous (22 Pairs)

Objective 4 • Compare haploid and diploid cells. n Gametes (sex cells) 2 n

Objective 5 • Predict how changes in chromosome number or structure can affect development.

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Chapter 6 Chromosomes and Cell Reproduction Why It’s Important Cells must copy their chromosomes and divide properly in order to make new cells that function properly ________ 4 -day old mouse cells Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 6 Section 1 Chromosomes Objectives • Identify four examples of cell division in eukaryotes and one example in prokaryotes. • Differentiate between a gene, a DNA molecule, a chromosome, and a chromatid. • Differentiate between homologous chromosomes, autosomes, and sex chromosomes. • Compare haploid and diploid cells. • Predict how changes in chromosome number or structure can affect development. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

6 -1 Vocabulary • • Gamete Binary fission Gene Chromosome Chromatid Centromere homologous chromosome • • • Diploid Haploid Zygote Autosome Sex chromosome karyotype Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 6 Section 1 Chromosomes Formation of New Cells by Cell Division reproduction • Cell division, also called cell _________, occurs in humans and other organisms at different times in their life repair ____ growth _____ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• Before a cell can divide, the DNA must first be copied and then ________ distributed to _____ new cells • Why does each new cell need an identical copy of DNA? DNA codes for the proteins made by the cell…incorrect DNA will lead to altered proteins Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• Prokaryotes carryout a very simple type binary of cell division called _______ fission ______ – Occurs in two stages: copied • 1 st DNA is _______ • 2 nd the original cell divides two new cells into _______ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• The original cell divides by adding membrane a new cell _______ between the copied DNA • As new material is added, the pinches in membrane _____ wall • Next, a new cell ______ forms around the membrane • Last, the original cell pinches off identical into two ________ cells Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

asexual • Binary fission is a form of _________ reproduction because…. single – It only involves a _______ parent that exact passes ______ copies of its DNA to its offspring exact copies of the – So the offspring are _____ parent prokaryotic cell. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Eukaryotic Cells • Before eukaryotic cells divide, their DNA is ______ and referred uncoiled to as ________ chromatin double • Recall that DNA is a _______ helix made up of subunits called nucleotides _________ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• Your DNA is normally uncoiled code it contains is because the _____ being used to make proteins ________ • Recall that specific segments of your genes DNA, called ______, code for the production of _______ different proteins Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• Before a eukaryotic cell divides, the DNA is ______, and it _____ up to form a copied coils chromosome • First, DNA coils around histones proteins called _____ to form small structures nucleosomes called _______ nucleosome Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• Chromosomes have two ________ sides identical because they contain DNA that copied has already been ______ • Each side is called a sister chromatid and they are _______ attached at a point called a centromere _________ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• These sister chromatids separate at the ________ centromere during cell division to ensure that each new cell has the same genetic information as _____ the original cell Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 6 Section 1 Chromosomes Different species contain different numbers of chromosomes Ex: Humans have ______ 46 chromosomes while a dog has 78 _______ chromosomes Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Asexual Reproduction – Eukaryotic cells exact copies of • Eukaryotic cells will make _____ themselves during asexual reproduction for four different types of cell division – One type is simply for __________ reproduction – Eukaryotes may also make new cells for repair _________, or growth ___________ development Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• Asexual reproduction only occurs in body cells which are also called __________ cells somatic • Examples of somatic cells are ________, skin muscle _______, and ________ cells nerve • You want these new cells to do the same job as their parent cell, so it is good that they make exact _____of copies each other • Overtime…the ends of your DNA strands start to deteriorate so your cells ______ age and change slightly even though they are “copies” Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

46 chromosomes, • All of your somatic cells contain ____ diploid cells which means they are _____ 2 n • A diploid cell is mathematically written as ______, sets of which means they have two _______ chromosomes… mother – you inherit one set from your _______ and father ______ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Sexual Reproduction – Eukaryotic Cells One pair of your chromosomes are called your • ______ sex _______ chromosomes, because they are involved gender with determining your ______ • Your other 22 pairs of chromosomes are called autosomes ________ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

X • Your two sex chromosomes are referred to as _____ Y and _____ – You inherit one from each parent XY = male • ______ XX = female • ______ • Females can donate only X’s while males can donate an X or a Y… • Do males or females determine the sex of an offspring? males Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

sex • Your _____ cells reproduce sexually because two cells are needed to make another cell ______ gametes • Your sex cells, also called _________, sperm cells egg consist of ____ or _____ • Gametes are _______ haploid cells, which are written n mathematically as ______, meaning they have a one _______ set of chromosomes Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• If human somatic cells (2 n) have 46 chromosomes…how many chromosomes do gametes (n) have? 23 • When two gametes _______, they make a unite diploid body cell in the process of ________ fertilization zygote – This fertilized cell is called a ______ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• Interesting Question… – If a zygote divides and grows through mitosis, how does our body contain so many different types of cells? embryos • Developing _________ consist of ______ cells that have the ability to stem differentiate __________ into different cells – Adults have _______ stem cells too, but scientists currently think that their ability to differentiate is limited ________ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

` In order for sexual reproduction to occur, organisms must inherit homologous ______ chromosomes, which are similar in shape ____, size ____, and content genetic _____ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

According to the diagram, how many chromosomes would the zygote of a human offspring contain if gametes had 46 chromosomes instead of 23? 92 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

That would be bad! Having too many or too few chromosomes can result in _______ mutations Abnormalities in chromosome # can be detected in a ________, karyotype which is a ____ photo of the chromosomes in a dividing cell that shows the chromosomes arranged by ______ size Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Sometimes an individual may inherit an incorrect number of chromosomes if the chromosomes fail to ___________ properly separate nondisjunction • This type of error is called __________ • One well known disorder that results from Down _______ nondisjunction is ______ syndrome Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

• Example: Down syndrome This condition is also trisomy called _______ 21 because it _____ 3 results from having ___ sets of chromosome 21 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 6 Section 1 Chromosomes You can also identify sex in a karyotype Does this karyotype show a male or female? male Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 6 Section 1 Chromosomes Your sex chromosomes are the only chromosomes that are not ________ homologous because they are different in structure ________ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chromosomal Mutations • Breakage of a chromosome can lead to four types of mutations that are usually ______ in animals fatal deletion – ________ duplication – ________ inversion – ________ translocation – ________ Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Deletion • Occurs when a gene from a chromosome breaks off or is ________ removed during division 1 1 2 2 3 4 A new cell will lack _____ a certain gene and protein the _____ it coded for 4 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Review • How is a gene deletion different from a deletion in a frameshift mutation? Deletes nucleotides…not entire genes Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Duplication attaches • Occurs when a chromosome fragment ______ to its homologous chromosome 1 1 2 2 3 1 A new cell will extras of have ____ certain genes and proteins the _____ it coded for 4 2 3 4 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Inversion • Occurs when a chromosome fragment breaks off and order reattaches in the wrong ______ 1 2 3 4 1 2 4 3 Genes will be out of order ______ and certain not proteins may _____ be made Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Translocation • Occurs when a chromosome fragment breaks off and nonhomologous attaches to a ____________ chromosome The gene may not used be _____ 1 2 3 4 because it is on the wrong chromosome 1 2 3 4 9 Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Objective 1 • Identify four examples of cell division in eukaryotes and one example in prokaryotes. reproduction Binary fission repair growth development Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Objective 2 • Differentiate between a gene, a DNA molecule, a chromosome, and a chromatid. Gene – Segment of a DNA that codes for a protein Chromosome – coiled DNA molecule (x shape means it has been copied already) Chromatid – identical copy of DNA found in a chromosome…held together by centromeres Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Objective 3 • Differentiate between homologous chromosomes, autosomes, and sex chromosomes. Homologous (22 Pairs) Nonhomologous… determine gender Chapter menu Similar in Structure Size & genetic Content (genes) Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Objective 5 • Predict how changes in chromosome number or structure can affect development. Number – Trisomy 21 Structure – Deletion, duplication, inversion, translocation Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.