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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
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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.
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6-1 Vocabulary Gamete Binary fission Gene Chromosome Chromatid
Centromere homologous chromosome Diploid Haploid Zygote Autosome Sex chromosome karyotype
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Formation of New Cells by Cell Division
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
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Before a cell can divide, the DNA must first be __________ and then _______________ to new cells
Why does each new cell need an identical copy of DNA? copied distributed DNA codes for the proteins made by the cell…incorrect DNA will lead to altered proteins
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1st DNA is _____________
Prokaryotes carryout a very simple type of cell division called ______________ ___________ Occurs in two stages: 1st DNA is _____________ 2nd the original cell divides into _______ new cells binary fission copied two
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The original cell divides by adding a new cell _____________ between the copied DNA
As new material is added, the membrane _________ in Next, a new cell ____________ forms around the membrane Last, the original cell pinches off into two _______________ cells membrane pinches wall identical
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asexual single exact exact
Binary fission is a form of _________________ reproduction because…. It only involves a _____________ parent that passes ___________ copies of its DNA to its offspring So the offspring are __________ copies of the parent prokaryotic cell. single exact exact
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Eukaryotic Cells uncoiled chromatin double nucleotides
Before eukaryotic cells divide, their DNA is ____________ and referred to as _______________ Recall that DNA is a _____________ helix made up of subunits called _________________ uncoiled chromatin double nucleotides
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code proteins genes different
Your DNA is normally uncoiled because the _________ it contains is being used to make _______________ Recall that specific segments of your DNA, called ___________, code for the production of _____________ proteins code proteins genes different
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copied coils histones nucleosomes nucleosome
Before a eukaryotic cell divides, the DNA is ____________, and it __________ up to form a chromosome First, DNA coils around proteins called _________ to form small structures called ______________ copied coils histones nucleosomes nucleosome
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Next, the nucleosomes actually end up coiling __________ on themselves to form a _________________
twice supercoil
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This supercoil is tightly packed in a structure called a ________________
chromosome
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identical copied chromatid centromere
Chromosomes have two ________________ sides because they contain DNA that has already been ____________ Each side is called a sister _____________ and they are attached at a point called a _________________ identical copied chromatid centromere
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These sister chromatids _______________ at the centromere during cell division to ensure that each new cell has the _________ genetic information as the original cell separate same
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Chapter 6 Section 1 Chromosomes Different species contain different numbers of chromosomes Ex: Humans have ______ chromosomes while a dog has _______ chromosomes 46 78
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Asexual Reproduction – Eukaryotic cells
exact Eukaryotic cells will make _________ copies of themselves during asexual reproduction for four different types of cell division One type is simply for ___________________ Eukaryotes may also make new cells for _________________, ________________, or _____________________ reproduction repair growth development
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somatic skin muscle nerve copies age
Asexual reproduction only occurs in body cells which are also called ___________________ cells Examples of somatic cells are _______________, _____________, and ________________ cells You want these new cells to do the same job as their parent cell, so it is good that they make exact __________of each other Overtime…the ends of your DNA strands start to deteriorate so your cells ______ and change slightly even though they are “copies” somatic skin muscle nerve copies age
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46 diploid 2n sets mother father
All of your somatic cells contain ____ chromosomes, which means they are _________ cells A diploid cell is mathematically written as ______, which means they have two _______ of chromosomes… you inherit one set from your _____________ and ____________ diploid 2n sets mother father
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Sexual Reproduction – Eukaryotic Cells
______ pair of your chromosomes are called your _______ chromosomes, because they are involved with determining your ____________ Your other 22 pairs of chromosomes are called ________________ sex gender autosomes
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X Your two sex chromosomes are referred to as _____ and _____ You inherit one from each parent ______ = male ______ = 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? Y XY XX males
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sex two gametes egg sperm haploid n one
Your _________ cells reproduce sexually because ______ cells are needed to make another cell Your sex cells, also called _________________, consist of ________ or _________ cells Gametes are _____________ cells, which are written mathematically as ______, meaning they have a _____________ set of chromosomes two gametes egg sperm haploid n one
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23 unite fertilization zygote
If human somatic cells (2n) have 46 chromosomes…how many chromosomes do gametes (n) have? When two gametes _____________, they make a diploid body cell in the process of _______________ This fertilized cell is called a ____________ 23 unite fertilization zygote
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mitosis adult into an ___________ organism
` The zygote will then continue to grow and develop through ____________ into an ___________ organism mitosis adult
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embryos stem differentiate stem limited Interesting Question…
If a zygote divides and grows through mitosis, how does our body contain so many different types of cells? Developing _________________ consist of ____________ cells that have the ability to ___________________ into different cells Adults have _______ cells too, but scientists currently think that their ability to differentiate is ________________ embryos stem differentiate stem limited
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homologous shape size content
` In order for sexual reproduction to occur, organisms must inherit ____________ chromosomes, which are similar in ________, ________, and genetic __________ homologous shape size content
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` Your 46 chromosomes are actually ____ sets or pairs of homologous chromosomes
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According to the diagram, how many chromosomes would the zygote of a human offspring contain if gametes had 46 chromosomes instead of 23? 92
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mutations karyotype photo size
That would be bad! Having too many or too few chromosomes can result in _____________ Abnormalities in chromosome # can be detected in a ________________, which is a ________ of the chromosomes in a dividing cell that shows the chromosomes arranged by ___________ mutations karyotype photo size
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separate nondisjunction Down syndrome
Sometimes an individual may inherit an incorrect number of chromosomes if the chromosomes fail to ______________________ properly This type of error is called ___________________ One well known disorder that results from nondisjunction is ___________ ______________ separate nondisjunction Down syndrome
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trisomy 21 3 Example: Down syndrome This condition is also
called _____________ _____ because it results from having ___ sets of chromosome 21 trisomy 21 3
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Chapter 6 male You can also identify sex in a karyotype
Section 1 Chromosomes You can also identify sex in a karyotype Does this karyotype show a male or female? male
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Chapter 6 homologous structure Your sex chromosomes are the only
Section 1 Chromosomes Your sex chromosomes are the only chromosomes that are not _______________ because they are different in homologous structure
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Chromosomal Mutations
Breakage of a chromosome can lead to four types of mutations that are usually ___________ in animals _______________ fatal deletion duplication inversion translocation
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Deletion removed 1 2 3 4 lack 1 2 4 protein
Occurs when a gene from a chromosome breaks off or is _______________ during division removed A new cell will __________ a certain gene and the __________ it coded for lack protein
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Deletes nucleotides…not entire genes
Review How is a gene deletion different from a deletion in a frameshift mutation? Deletes nucleotides…not entire genes
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Duplication attaches 1 2 3 4 extras proteins 1 2 1 2 3 4
Occurs when a chromosome fragment ___________ to its homologous chromosome A new cell will have ________ of certain genes and the __________ it coded for extras proteins
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Inversion order 1 2 3 4 out not 1 2 4 3
Occurs when a chromosome fragment breaks off and reattaches in the wrong ____________ order Genes will be ______ of order and certain proteins may _____ be made out not
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Translocation nonhomologous used 1 2 3 4 1 2 3 4 9
Occurs when a chromosome fragment breaks off and attaches to a ________________________ chromosome nonhomologous The gene may not be _________ because it is on the wrong chromosome used
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Objective 1 reproduction Binary fission repair growth development
Identify four examples of cell division in eukaryotes and one example in prokaryotes. reproduction Binary fission repair growth development
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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
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Size & genetic Content (genes) Homologous (22 Pairs) Nonhomologous…
Objective 3 Differentiate between homologous chromosomes, autosomes, and sex chromosomes. Similar in Structure Size & genetic Content (genes) Homologous (22 Pairs) Nonhomologous… determine gender
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Objective 4 n Gametes (sex cells) 2n Somatic (body cells)
Compare haploid and diploid cells. n Gametes (sex cells) 2n Somatic (body cells)
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Structure – Deletion, duplication, inversion, translocation
Objective 5 Predict how changes in chromosome number or structure can affect development. Number – Trisomy 21 Structure – Deletion, duplication, inversion, translocation
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