Unit 3 Lecture 1 part 1 10/13/22 Flashcards
_____is the transmission of traits from one generation to the next
Heredity
_____ is the scientific study of heredity and variation
Genetics
_____are the units of heredity and are made up of segments of DNA which code for specific proteins
Genes
Genes are passed to the next generation via reproductive cells called __________(sperm and eggs)
Gametes
Most DNA is packaged into __________
Chromosomes
For example, humans have __________ chromosomes in their somatic cells
46 or 23pairs
Each gene has a specific position, or __________, on a certain chromosome
Locus
In __________, a single individual passes genes to its offspring without the fusion of gametes
Asexual reproduction
A __________ is a group of genetically identical individuals from the same parent
clone
In __________, two parents give rise to offspring that have unique combinations of genes inherited from two parents
sexual reproduction
A __________ is the generation-to-generation sequence of stages in the reproductive history of an organism
Life cycle
Human somatic cells have __________ of chromosomes
23 pairs
A __________ is an ordered display of the pairs of chromosomes from a cell
karyotype
The two chromosomes in each pair are called __________, or homologs
homologous chromosomes
The __________, which determine the sex of the individual, are called X and Y
sex chromosome
Human females have a __________ chromosomes (XX)
homologous pair of x
Human males have __________ chromosome
one Y and X
The remaining 22 pairs of chromosomes are called __________
autosomes
A __________ cell (2n) has two sets of chromosomes
Diploid
For humans, the __________ number is 46 (2n = 46)
diploid
A 1.__________(sperm or egg) contains a single set of chromosomes and is 2.__________(n)
1.Gamete
2.haploid
For humans, the haploid number is __________(n = __________)
23
Each set of 23 consists of __________ and a __________ chromosome
- 22 autosomes
- single sex
In an unfertilized egg (ovum), the sex __________
chromosome is x
In a sperm cell, the sex chromosome may be __________
either x or y
__________ is the union of gametes (the sperm and the egg)
Fertilization
The fertilized egg is called a __________ and has one set of chromosomes from each parent
zygote
The zygote produces somatic cells by __________ and develops into an adult
mitosis
__________ are the only types of human cells produced by __________ rather than mitosis
1.gametes
2.meiosis
__________ results in one set of chromosomes in each gamete
meiosis
__________ are the only haploid cells in animals
gametes
They are produced by __________ and undergo __________ further cell division before fertilization
1.meiosis
2.no
Plants and some algae exhibit an __________
alternation of generations
In plants a __________ makes haploid gametes by mitosis
gametophyte
In plants, fertilization of gametes results in a diploid __________
sporophyte
In plants, only ________ cells can undergo meiosis
diploid
Meiosis takes place in two sets of cell divisions, called 1._______ and 2.______
meiosis I
meiosis II
in meiosis the 2 cell divisions result in ____ daughter cells, rather than the 2 daughter cells in mitosis
4
In meiosis each daughter cell has only ___ as many chromosomes as the parent cell
half
in meiosis a single pair of homologous chromosomes in a diploid cell, both members of the pair are ______
duplicated
Homologs may have different versions of genes, each called an ___
allele
Homologs are not associated in any obvious way except during ____
meiosis
__________ halves the total number of chromosomes very specifically
Meiosis
In the __________ meiotic division, homologous pairs of chromosomes pair and separate and In the second meiotic division, sister chromatids of each chromosome separate
first
After the second meiotic division, ____ new haploid cells are produced as a result
Four
