inheritance (topic 17)

Question 1

chromosome

Answer 1

DNA in the nucleus of a cell is coiled and packed to form a thread-like structure,
chromosomes are made of DNA,
which contains genetic information in the form
of genes

Question 2

gene

Answer 2

a length of DNA that codes for a
protein

Question 3

dna

Answer 3

A large molecule made from bases, and which carries genetic information in the form of genes.

Question 4

allele

Answer 4

An alternative version of a gene. A section of DNA that codes for a particular protein

Question 5

what is the chromosome responsible for sex

Answer 5

XY chromsomes
xx= female
xy= male

Question 6

haploid nucleus

Answer 6

a nucleus containing a single set of unpaired chromosomes. eg. gamete= 23 chromosomes

Question 7

diploid nucleus

Answer 7

a nucleus containing two sets of chromosomes, for example in body cells.= 46 chromosomes (23 pairs)

Question 8

how is sex inherited

Answer 8

each person inherits one sex chromsome from father and one from mother
sperm cell is either x or y
egg is always x

Question 9

describe dna

Answer 9

two strands that coil together to form a double helix each strands contain complementary chemical substances called bases
T-A
C-G

Question 10

genetic code

Answer 10

The sequence (order) of bases differs from gene to gene. The sequence of bases in a gene is its genetic code: it determines the order in which amino acids are joined together to make a specific protein

Question 11

what does the sequence of bases in a gene determine

Answer 11

the sequence of amino acids used to
make a specific protein and different sequences of amino acids result in different shaped protein molecules

Question 12

how does dna control cell function

Answer 12

DNA controls cell function by
controlling the production of proteins, including enzymes, membrane carriers and receptors for neurotransmitters

Question 13

describe process of making proteins (protein synthesis)

Answer 13

-protein syntehsis occurs in ribosomes found in the cytoplasm
1. dna moelcule in nucleus unzips, exposing bases in gene
2. Mrna molecule formed using exposed bases in unzipped dna strand as template, bases in mrna bind with complementary bases in dna, mrna molecule carries a copy of the gene
3. mrna molecule moves out of the nucleus into the cytoplasm
4.ribosome reads mrna codes and joins amino acids to form protein follwoing specific base sequence in the mrna

Question 14

true or false most body cells in an organism
contain the same genes, but many genes in a particular cell are not expressed because the cell only makes the specific proteins it needs

Answer 14

true

Question 15

mitosis

Answer 15

nuclear division giving rise to
genetically identical cells, cells produced are called daughter cells

Question 16

fucntions of mitosis

Answer 16

cell repair/ replacement, assexual reproduction, tissue repair,

Question 17

describe path leading to mitosis

Answer 17

1. each chromosome is replicated exactly so that there are two copies of each chromosome
2. chromosome join together into middle of cell
3. when nucleus divides into two, a copy of each chromosome goes into each new cell

Question 18

stem cells

Answer 18

unspecialised cells that divide by mitosis to produce daughter cells that can become specialised for specific functions

Question 19

meiosis

Answer 19

reduction division in which the chromosome number is halved from diploid involved in production of gametes

Question 20

where are male gametes and female gametes produced

Answer 20

feamle- ovaries
male- testes

Question 21

inheritance

Answer 21

the transmission of genetic information from generation to generation

Question 22

phenotype

Answer 22

observable feature of an orgnaism

Question 23

genotype

Answer 23

genetic make-up of an organism in terms of its alleles

Question 24

homozygous

Answer 24

two identical alleles

Question 25

heterozygous

Answer 25

two different alleles

Question 26

pure breeding

Answer 26

two identical homozygous individuals
that breed together will be pure-breeding all their offspring will inherit the same alleles, and show the same phenotype as their parents

Question 27

monohybrid cross

Answer 27

Breeding two individuals that differ in their alleles for a particular gene.

Question 28

dominant allele

Answer 28

always expressed if it is present (uppercase letter symbol)

Question 29

recessive allele

Answer 29

only expressed if the dominant allele is not present. (lower case letter symbol)

Question 30

pedigree diagram

Answer 30

A type of family tree that shows the inheritance of a feature.
squares= males
circles= females

Question 31

what is meant by a carrier

Answer 31

An individual who has a single copy of a recessive allele that is responsible for a genetic disorder or disease.

Question 32

test cross

Answer 32

A cross with a homozygous recessive individual, used to determine the genotype of an individual showing the dominant trait.

Question 33

codominance

Answer 33

A situation in which two different alleles for a gene influence the phenotype to the same extent, for example in human ABO blood groups.

Question 34

what are the alleles for blood

Answer 34

I^a I^b I^o

Question 35

sex linked characteristic

Answer 35

a feature in which the gene responsible is located on a sex chromosome and that this makes the characteristic more common in one sex than in the other eg. red green color blindness

Question 36

describe red green colour blindness

Answer 36

sex linked chcaractersitic carried in x chromsome, which is recessive, meaning feamles have a fewer chance of getting the disease, as man only need to inherit one copy of the gene to gain the disease, while feamles must carry both, if only one recessive gene present female is a carrier